Alright so let's talk about Vayne Any hp you build is negated by her Silver Bolts so what item do we use to counter her? Currently the only way through items is Frozen Heart and Randuin's Omen. Secondly, you can build whatever you feel is needed, generally, Vayne is very difficult to deal with in terms of out playing her as the only way to do so is to dodge her E. Generally, if you fail to do so and aren't very ahead, you'll probably die. Crit Yi deals with vayne the best in my eyes unless guinsoo's is already stacked.

Basically, you can go rageblade second but the way I see it is, why build defensivly if i'm going to die anyway? I may as well at least go 1 for 1 rather than 1 for 0.

If you build lord dominicks, and Blade Of The Ruined King, you'll find you'll kill both tanks and squishies very quickly unless it's a rammus or so. On hit is better to play in jungle because it's easier to snowball, and maintain that snowball, as well as easier to come back from when behind. Crit is better when played in lane.

I'll give it a whirl in some games I guess, but imo warrior isn't that good and the eye ball collection even if it's fully stacked only grants 18 AD which is pretty much nothing since it's more of a late game rune that doesn't offer much late game.

I'd say a better path is going your blue smite, and going up front critical strike with an infinity edge > pd > shiv, your aim is to snowball, not delay your spikes.

Celerity is pretty strong yeah, but wouldn't ghost be better than ignite? Ignite, sure gives you damage, but having a summoner spell to escape would be better imo. Also ghost gives like 5 AD or so thanks to Celerity.

Hello, thanks for the question

1. Basically, use common sense. If you think you're about to be in a fight, save your Wuju Style if you plan on farming, use it. By the time you get to the next camp, it will be up, or at least by the time your next Double Strike on the next camp is up. Maximise damage via activating Wuju Style just before the Double Strike connects as it ensures you get maximum use of it. When you get bloodrazer, it doesn't really matter whether you use it or not, but early jungling try to use it as much as possible.

2. Fervor did get nerfed but that doesn't mean we don't use it, Fervor of Battle is the best mastery to use on Yi, warlords only becomes effective when you have around 20% hp, and dealing more damage is better than sustain, by not taking fervor, your ganks become weaker. The only time it's worth going warlords is when you're in lane as it gives lane sustain. Thunderlord's Decree is also a viable lane mastery, but falls of compared to fervor.

3. Lethality marks is a waste as you don't really need pen, you do plenty damage with e, and other on hits. More hits = more Wuju Style procs and more Double Strike as well as bloodrazer procs. If you choose critical strike Yi, obviously you're AD so Wuju Style deals more damage, and more attacks = more crits. On top of that, if they stack armor Last Whisper has got your back. AS in the jungle is better than flat AD as you're applying the machete passive more as it gives +25 bonus damage on hit, you're getting more double strikes, and you're applying wuju style more. The clear speed is about even if not slightly better with AS marks. The reason you use AD is in lane due to trades being shorter due to minion aggro, towers and other reasons thus dps not really mattering as much, on top of easier csing.

4. I would choose neither to be honest, my life steal items of choice are: Blade of the Ruined King if i'm on hit, and if i'm crit yi, i choose Mercurial Scimitar due to the qss active being a must if you're that squishy, on top of the mr it provides. But if you're just asking which is better, bloodthirster wins by far, sure the q heal is somewhat nice, but if you hit 4000 damage with a 4 hit aoe q crit with death's dance (1000 damage each) Unlikely, but let's say it happened, this = 15% of 4000 = 600, however aoe heals are reduced by 33% so only a 198 heal if you somehow managed to hit 4000 with an alpha, and obviously this will never happen in an actual game. Since alpha strike is your only ability, it's your only source of healing from Death's Dance thus not worth buying over bloodthirster due to it giving an over healing passive which makes you harder to kill, on top of healing 5% more health.