Hi I'm jjuns, an ADC main on NA and I have been playing League of Legends for 7 years.
I want to bring you guys a series of ADC guides, starting with Lucian.

Table of Contents
1. Why Lucian?
2. Combos - Optimizing Damage
3. Base Timings - Items/Tempo
4. Early Game - Laning Phase
5. Mid Game - Rotations
6. Late Game - Objective Focus

Lucian is a flashy mechanical marksman with a very strong early game that has the ability to snowball a lane and become a potential carry threat into the later stages of the game. Because of his mobility, he can follow up on engages swiftly where other marksmans have difficulty doing so.

Lucian provides a lot of safety but also a big range of threats due to his built in dash. This is the biggest difference in playstyle that separates Lucian from other marksmen. If we think about it in terms of summoner spells, it is like having another Flash available on a very short cooldown. Relentless Pursuit allows him to capitalize on enemies' positioning mistakes, often resulting in summoners blown or a kill just by knowing when and where to dash in. Because of his mobile nature, Lucian can also be used as a counterpick to heavy engage comps, like when the enemy team has a lot of ways to close the gap or lock you down with crowd control(e.x hooks/Jarvan/Ashe/Varus/etc).

Mastering Lucian can help you improve your game in a way other marksmen can't. Lucian takes limit testing to the next level. A lot of you have probably heard of Faker's famous line, "I got him," before a kill is even about to happen. It almost seems supernatural, but it all has to do with foresight. Foresight regarding damage output, trading patterns vs specific champions, positioning, cooldowns, and everything you can think of is taken into account in a matter of seconds. This is probably why I enjoy playing Lucian so much, there is always something you can improve on so it never gets boring.

League is a game where each and every single decision you make, starting from champion select and runes and even the items you buy from fountain at 0:00, will influence how the rest of the game plays out. Playing Lucian at the highest level will enable you to drastically skew the flow of the game in your favor. If you love the "outplaying" aspect of League, give Lucian a try.

Lucian's strength lies in his quick burst damage(almost like an ADC Assassin), dishing out all of his damage while the opponent AD can only retaliate with a few autos. All marksmen rely on combos to efficiently deal damage, but comboing properly on Lucian can make or break a player - it is essential to understand the timing of your combos because it is the difference between missing out on all your burst damage vs deleting an enemy instantly. One auto attack cancel can drastically change the outcome of a trade or teamfight. This is even more relevant now with the new rune, Press The Attack.

Combos are about maximizing your damage over a fixed window of time. How do we do this for Lucian? Well first, we need to consider the rune Press the Attack - a rune that synergizes so well with Lucian I think Riot made it specifically for him. Lucian can abuse this rune because of his passive, Lightslinger, which shoots out two autos for one basic attack after using an ability. Press the Attack procs when you hit the same enemy champion with 3 consecutive basic attacks, so by making use of his passive, no other ADC can take greater advantage of PTA than him. If we think about pure damage output with no regard for the situation, we always want to proc PTA first, as it makes the enemy target vulnerable and take increased damage from all sources.

In a perfect world, Lucian's go to combo would always start like this: Auto - E(proc PTA). This way, all subsequent damage will be increased by PTA. But a lot of the times, you won't have access to this combo because most people guard and position themselves against this. There's also the question of whether or not you should even use your dash in this way(instead, maybe save dash to dodge a skillshot, or for disengage). So this means we have to adjust our combos to the circumstances presented to us.

Often times, the trade off is between getting the most out of your damage vs. doing the most damage in the shortest amount of time. These two things are not always mutually exclusive though.

Here are a list of Lucian combos you should familiarize yourself with:

Dash-In Burst Combo
E - AA - Q - AA - W - AA - Back Off/Chase

This is THE basic combo to go for, as it gives you the most damage output in the time it takes to finish this combo. A lot of the times you will need to use your dash to get in range of your first auto, so it starts off using your dash with no auto cancel. In an extended 1v1, you could opt to go for another auto before using Q to proc PTA.

Optimal Combo
AA(Assuming you are in 500 range already) - E - AA - Q - AA - W - AA

This is the most devastating combo, but at the cost of using your dash as an auto reset instead of dodging or retreating.

Niche Combos
Starting with E
1) E - W - AA - Q - AA : For chasing when you need the extra range on W to hit enemy.
2) E - R : For reach, when E will not bring you into 500 range
3) E - W - R : For reach + chase, can use when running away too as Culling on top of W will give you move speed to create more distance in between you and enemy.
4) E - AA - W - AA - Q : Ever have a moment where they dodge your Q? This combo plays around opponents who expect your Q to come right after your dash, and the extra movespeed from W helps you stick on them.

Starting with W
1) W - AA : Often for small trades, good for poke and against long range ADCs
2) W - E - AA : Variation of E - W, this combo is more efficient as it cancels W cast time. Faster chase potential.
3) W - R : Great for movespeed and reach

Starting with Q
1) Q : Only reason to start with Q is if you are looking for poke through minions. I probably use this the most in lane surprisingly, as it helps cover your 500 range weakness.

Starting with Auto Attack
(My favorite way to trade but not many opportunities to use this, problem is your 500 range which opens you up to taking a lot of damage, and it is slow)
1) AA - Q - AA
2) AA - W - AA
3) AA - R - AA

Starting with R
Lucian's ultimate Culling is versatile. I usually do not like to use Culling when I am in auto range because often times you are foregoing free auto damage, when you could use culling after they use their flash or dash(if they have one too) to snipe them off. Culling to chunk their HP and not to kill is also viable, which will then increase your kill threat. Wave clearing with R is also an option you should consider.

Generally, you want to squeeze in your passive in between every ability for the most damage. A tip that a lot of players don't know about Lucian is that his dash can be executed in 2 ways. Long dash and short dash. Long dash is for covering distance and short dash is to release your autos faster, making way for even faster damage output when utilizing relentless pursuit. Another tip is using the active on your Bilgewater Cutlass/Blade of the Ruined King after PTA procs for the extra damage.

Recalling to base is a very powerful tool. Timing your base correctly can enable you to move around the map with finesse. It's important to base at the right time because recalling is inherently a sacrifice. You lose pressure and presence on the map, miss out on potential exp, and on gold and objective control. You will be down in sheer numbers on the map if the enemy can force you to recall at a sub-optimal time. Therefore, you want to make use of recall when it's in your favor to do so, primarily through big item purchases or tempo swings.

Leads are often created by being ahead in farm, exp, or kills, but a lot of times, leads are cemented by forcing the enemy to recall. So, the worst case scenario for basing would be solely to replenish your HP. We want to avoid this at all costs.

On Lucian, the first big item buy we consider is Bilgewater Cutlass. Rush this item ASAP. This is Vamp Scepter(900g) + Long Sword(350g) + 350g = 1600g in total. If you happen to base with 300g and are unable to purchase a long sword, just invest in a dagger. Below 300g, consider pots, pink ward, refillable potion or faerie charm.

Having a plan:

It's important to plan ahead from champion select. Make any rune adjustments like Overheal vs. Triumph, Coup de Grace vs. Cut Down.

Think ahead for the 2v2 matchup and how you want to control waves - pull or push?This depends on how junglers path.

The earliest opportunity we get to use our combo is at Level 2. Lucian has a huge damage spike then, so be on the lookout to hit level 2 first and look for an all in - auto, dash in, passive double shot, Q, passive double shot. It is most optimal to get an auto in first so you can proc PTA immediately. Punishing enemies with an auto as they go for CS is a common technique, but on Lucian, you have to be careful because of his short range. It is easy to get out-traded when going for single auto trades. Bot lane is a 2v2 lane so make sure you know the strengths of your support and play WITH them.

Before starting lane, have an idea of how much gold you want to base with. Obviously this will vary with how the lane plays out, maybe you get a kill or get killed, or the laning phase becomes an extended farm battle. The rule of thumb is to base at a time when you will miss the least amount of minions. This involves either forcing the opponent AD to awkwardly recall or quickly crashing the wave into the enemy tower, and therefore resetting the minion wave.

Let's take a look at optimal gold levels to base at.
First is Vampiric Scepter(900g). This is a great time to look to base if the enemy AD is looking for a B.F Sword(1300g) on their first back. Basing at 1300g on their grounds would give them +40AD while you buy Vampiric Scepter(900g) + Long Sword(350g) = 25AD + 10% Lifesteal. Base at 900g and you force them to buy a Pickaxe(875g, 25AD) vs Vampiric Scepter(900g, 15AD + 10%LS), or they have to stay in lane to farm up another 400g, putting them in a disadvantageous position.

If you both end up basing at 1300g, it's not the end of the world. Lucian can still win trades through his explosive kit, so utilize his combos or look for an all in. You also have the advantage of having early Lifesteal for sustain.

Let's think of Mid Game as when the first outer turret is destroyed. Whichever team takes the first turret will have that much more room and time to move around the map for objectives and kills. In bot lane, if you take first turret, you can either choose to attack T2 or swap and push for other outer turrets. This depends on so many factors, even in the same matchups this flow can vary depending on how laning phase plays out. If you are the aggressor(you destroy first turret at bot) decide which lane will put you in the best position to continue attacking.

Some objectives to consider after taking first tower is:
-Is dragon still up?
-Is it safe to continue your siege towards tier 2?
-Does their mid/jg have strong roam and gank pressure?
-Can you take rift herald uncontensted?
-Is your mid/top in a bad matchup?
-Is the enemy team stronger grouped or split?

Usually you want to consider relieving pressure for your other lanes if they are already in a bad matchup and look to siege turret quickly 2v1 with your jungle supporting in the same area. It's often the case you want to attack top side if you have the choice between mid and top equally. When attacking mid, it is easier for the enemy to group and hold against the siege, creating a stalemate. This is the opposite of what you want to do when you are in the lead - you want to continue to increase the gap at a fast tempo.

If you are defending(enemy takes first turret), you want to slow down their push as much as possible. Just because they are in the lead, it does not mean you have to concede all objectives. Let's say they take first turret bot and are 3manning dragon with jg while their mid is in base. Your jungle is making a gank top but you have your mid in the vicinity. Definitely consider contesting the dragon. Naturally, when defending, you need to be more careful and let the enemy have their way. But at a certain point, risks must be taken. Otherwise, your team will be whittled down and starved, and there will be a point where it is too late to shift the tides of the game. Keep your eyes peeled and never stop looking for the right opportunity to attack.

It's important to know what stance your team should take(aggressor, neutral, defender). Keep in mind though, aggressor does not necessarily mean attack every objective, just as defender does not mean you have to give up everything. So read the state and flow of the game and make the right movements.

Once first tower falls, other turrets and objectives start falling like dominoes. For me, late game begins when either team can do baron. Baron is the ultimate trump card. Lost games are won through baron. Baron secures wins. The biggest throws and comebacks are around baron. Baron is your god. First, know at what point your team and the enemy has the power to take baron. As a bot lane, you generally want to stick to mid lane to have the greatest coverage of the map and access to baron. The easiest way to take baron is when you can do it without enemies knowing, or when they simply cannot reach baron in time. It is rare to attempt to take baron when there is no one dead. Baron calls are more confidently made when there is a numbers advantage. Watch for death timers. Start baron if your team is stronger, make sure your jungler is there with smite. Don't be afraid to turn and look for a fight if it is being contested.

Another big late game objective is inhibitors, once you take an inhibitor it opens you up to focus on the other remaining lanes, while they have to constantly clear waves or risk losing nexus towers.

How does Lucian fit into all this? We know he's a bad sieger(500 range) and he doesn't offer utility(CC) to his team. It comes back to his dash and insane burst damage. To maximize Lucian on the rift, you have to play as bait. Your 500 range when sieging is bait to lure the enemy, make them think they have you while you look for the outplay. You offer a ton of damage for your team. Surprise the enemy with your one shotting capabilities. Kite them into oblivion.