Cassiopeia is what you would call a "DPS Caster." Her skillset involves low cooldown DoT (damage over time) spells, and will involve a lot more micromanagement than the usual champion. Also, she's very very squishy, and with her kit being the opposite, it makes her worthy of the full "Hard" difficulty bar in her champion description.

However, she is not impossible to play. She just needs a good team comp, and a good player to control her. Watching your cooldowns more often is one skill you need to develop.


VERSION HISTORY
1.5 - 16AUG2011 - Bought Cass, more experience with her, meaning new build for much more damage. Also removed WIP tags.
1.1 - 14APR2011 - Updated for recent changes on Cassiopeia
1.0 - 06APR2011 - Started guide for Cassiopeia

Pros
+ Very strong lane champion early game, especially in a solo lane.
+ AOE harrass
+ Low cooldowns

Cons
- Scales poorly over time if not farmed enough
- Very squishy
- Very high skillcap, one of the highest out of all AP carries.

Surprisingly, Cassiopeia has some pretty nasty nukes with her Q and E. It's just a tad risky to get into E range, but if you manage to counter-initiate or supplement a good initiate from your tank with your ultimate, you won't have to worry about getting whacked on the head. This build is designed to take full advantage of Cassiopeia's strong early game.

Greater Mark of Magic Penetration x 9
Greater Seal of Scaling Mana Regeneration x 9
Greater Glyph of Scaling Ability Power x 9
Greater Quintessence of Ability Power x 9

Itemization:
Doran's Ring Start x 2 - Starting with one early game and grabbing another + boots on your first B will give you enough AP and Mana Regen to put down the hurt on your lane.
Sorcerer's Shoes
Rabadon's Deathcap
Rylai's Crystal Scepter
Void Staff
Zhonya's Hourglass
Will of the Ancients or Banshee's Veil

Rod of Ages is still a great pick for Cassiopeia, but you'll have to know if you are going into lategame before you even touch Rabadon's Deathcap. Knowing this comes from experience. It's something I cannot teach.

This will give her an even more amazing early game, and good scaling late game. However, if you are really new to Cass or just don't have the runes, follow the older full build below.

Greater Mark of Magic Penetration x 9
Greater Seal of Replenishment x 9
Greater Glyph of Scaling Ability Power x 9
Greater Quintessence of Health x 2
Greater Quintessence of Scaling Ability Power x 1

- MagicPen reds are picked because come on, it's a standard caster rune.
- Flat MP5 yellows allows her to harrass a bit more early game, because of the flat amount. You can always substitute this for Greater Seal of Scaling Mana Regeneration if you want scaling from early to late game, though I feel that she could get enough mana in the end with this build.
- AP/Level blues enables her to scale properly as the game prolongs, especially since she does weaken as the game lengthens. Can be replaced with Greater Glyph of Cooldown Reduction
- Just 2 Flat HP quints will make her less squishy early game, providing an even stronger early game where she already excels. 1 flat AP quint will add more to her early game punch, as well.

Noxious Blast: Cassiopeia blasts an area with a delayed high damaging poison, dealing magic damage over 3 seconds and granting her movement speed for 2 seconds if she hits a champion.

Cooldown: 3 seconds
Cost: 35 / 45 / 55 / 65 / 75 Mana
Magic Damage: 75 / 115 / 155 / 195 / 235 (+0.9 per Ability Power)
Movement Speed: 15 / 17.5 / 20 / 22.5 / 25 %

Her Noxious Blast is your main "nuke," so maxing it out first is priority. It is also fairly tough to hit, as it does not have a skill target like most champions. It will land on wherever your mouse is hovered to. Max this first.




Miasma: Cassiopeia releases a growing cloud of poison that lasts for 7 seconds. Any enemy that passes through it is poisoned for 2 seconds, dealing magic damage each second and slowing them. Continual exposure renews this poison.

Cooldown: 9 seconds
Cost: 70 / 80 / 90 / 100 / 110 Mana
Magic Damage: 25 / 35 / 45 / 55 / 65 (+0.15 per Ability Power)
Slow: 15 / 20 / 25 / 30 / 35 %

Her Miasma is your CC. It's got a good AOE radius, and anyone who steps in it gets poisoned for 2 seconds, and will refresh while they are in the pool. Even if the damage is less than desirable, the slow effect is very good at both chasing and escaping.




Twin Fang: Cassiopeia deals magic damage to her target. If the target is poisoned then Twin Fang's cooldown is reduced to .5 seconds.

Cooldown: 5 seconds
Cost: 50 / 60 / 70 / 80 / 90 Mana
Magic Damage: 60 / 95 / 130 / 165 / 200 (+0.45 per Ability Power)

Her Twin Fang is your filler spell. If you hit them with your Q or E, you can unload a couple of them on someone. However, this is very risky because of its short range, and should only be used for champions who don't have a significantly powerful poke combo, like Irelia's Bladesurge-> Equilibrium Strike or LeBlanc's Sigil of Silence-> Distortion. Should only be used liberally on stunned/suppressed targets, or while chasing. This is NOT your main spell, and should be maxed out second.




Petrifying Gaze: Cassiopeia deals magic damage to all enemies in front of her. Enemies facing her are stunned for 2 seconds while enemies facing away are slowed.

Cooldown: 120 seconds
Cost: 120 / 160 / 200 Mana
Magic Damage: 200 / 325 / 450 (+0.6 per Ability Power)
Slow: 40 / 50 / 60 %
Stun: 2 Seconds

Her Petrifying Gaze is a cone AOE stun/slow. If a champion is facing you, they will be frozen for 2 seconds. If they are facing away, they will be slowed for 60% over 2 seconds. This is great for teamfights after it has been initiated, and everyone else has a target. You are bound to petrify at least 2 champions in the cluster. You can also use this to escape and counter-gank. Hit enemies with R, put a W and Q down, and run like hell.

CORE ITEMS
Sorcerer's Shoes
Rod of Ages - Cassiopeia's weakness is late game. Anything that scales with her is always a must
Rylai's Crystal Scepter - Cass needs health, and a lot of AP. This gives both. Also, the slow procs on all of your spells allow you to chase someone down.
Archangel's Staff - This item has great synergy with Rod of Ages. Since you do get an early Tear of the Goddess, you do not need to get this until you are done with Rylai's and RoA.

VIABLE ITEMS
Boots of Swiftness - Having more movespeed means you are able to pursue better, as well as position yourself easier with your Q and W.
Rabadon's Deathcap - More AP, the merrier. A very good caster item.
Banshee's Veil - This item is mainly for caster-heavy teams.
Quicksilver Sash - Malzahar's Nether Grasp or Warwick's Infinite Duress keep suppressing you? This'll save your life in more ways than one.
Zhonya's Hourglass - Mainly for it's active, this is also a good way to mitigate some physical damage. Also, it's great against Karthus's Requiem!
Lich Bane - Because you are hitting spells so fast, you are going to end up autoattacking with Lich Bane procs a lot.

QUESTIONABLE ITEMS
Morello's Evil Tome - The Mana Regen is nice, but the cooldown reduction is overkill for Cass. she already has a 3-second DOT, and a 0.5 filler spell (if you attack a poisoned target).
Mercury's Treads - Great for melee champions, not so much with casters. You shouldn't be hit by CC. If you do, you're already dead.
Ionian Boots of Lucidity - Same with Morello's, but even less viable.

Early Game
- Your early game is one of the best. You have AOE spells off the bat, and they are fairly long range. Take advantage of your passive to harass in bursts, instead of once every so often.
- Do NOT, I say, do NOT constantly harass with Twin Fang. It eats up too much mana early game.
- A hard CC lane partner is your best friend. Wait for them to CC, then place a W under them, then do a Q->R->R combo repeatedly.

Mid Game
- At this time, you should have a Rylai's along with either a Tear of the Goddess or Catalyst (depends if you are building ROA or Archangel's Staff first). This will allow all of your spells to slow the target 15% more, including Twin Fang. It's currently being discussed in the forum, but your E only hits for 15% slow, even if it is a single-target spell.
- You are an excellent poker. Keep hitting the enemy team with your Q (watch your mana!), until someone decides to initiate.
- Your R should be saved for when the majority of the team is clustered up. Learning when, where, and how to use it will make or break a Cassiopeia player. Of course, if there is someone flanking you, they get priority as they'll be facing you!

[EXAMPLE: We were pushing the inhibitor mid tower 3v5 when suddenly Warwick ults our Warwick from the side, leaving him by himself (but still near the tower. Of course, he gets priority for my R, saving our WW and killing theirs. We then pushed in and killed the turret and inhibitor.]

LATE GAME
- This is your weakest point, but do not let it discourage you. You are still a very good DPS character with your DOTs. Keeping your Miasma placed properly during a teamfight will eat up enemy HP, and allows you to spam Twin Fang. Not only that, you can also chase. If you have +3 boots, you can Ghost chase enemies, and slow them for your teammates. Certain champions with dashes and movement speed skills may evade you (Yi, Trynd, Shen, Mundo, to name a few), but everyone else is ezpz.

v1.0.0.122

Miasma modified to give persistent vision in the area where cast for the 7 seconds it lasts from giving vision for just an instant after cast.


v1.0.0.115

• Twin Fang cast animation sped up
• Petrifying Gaze
  --Cast animation sped up
  --Cast range increased to 850 from 700 (effect now roughly matches the particle)
  --Damage increased to 200/325/450 from 150/275/400
  --Cooldown reduction with rank is now reflected in the levelup tooltip
  --More accurately targets enemies that move in/out of the area during the cast time