Now, for anyone out there who doesn't appreciate the legendary abilities thrown out by a champion that requires very, very, specific timing and skill to master, let alone use, then please leave constructive CRITICISM, not just downvote and bad reason.

Cassiopeia, my favorite champion, also my ranked champion. This guide should teach you how to utilize and preform all of Cassiopeia's very nice abilities.The hardest character in the game, by far. Requires many hours of practice, tweaking and fine tuning to use right, however the rewards are worth the effort and more...

This guide is intended for those who have experience with Cassiopeia, not beginners, however if you pick up things fast, try it out.

Runes, fairly simple:

MARKS: Magic penetration marks for early-late game damage.

SEALS: Mana per 5 per level, makes it easier later in the game to spam your skills.

GLYPHS: Clearly I didn't go for ability power glyphs, however, usually a casters biggest weakness is another caster, especially against Cassiopeia, I've taken down countless amounts of Master Yi, and Mordekaiser, even a few Lee Sins and Udyrs too. But Cassiopeia is mostly weak to casters like Leblanc, who can hit you outside your range, along with Brand and anyone else along those lines.

QUINTESSENCES: Cooldown per level quints allow quick spamming of noxious blast and miasma, along with faster fire rate on twin fang. This also makes you deadlier in teamfights, seeing as how you almost always have your ultimate up now.

RUNES ARE SUBJECT TO CHANGE!

Masteries are a basic 9-0-21. The only reason I got one point in deadliness was so I could continue to spend the points on offense. Right off the bat you have a 9% cooldown reduction with masteries alone, giving Miasma it's time to shine. Only bother to tree up to Archaic Knowledge, because nothing else on the tree is that useful. The extra movement speed also helps in the beginning, with slightly better dodging. Blink of an Eye, obvious choice while using flash.

Doran's Ring

Sorcerer's Shoes

Zhonya's Hourglass

Will of the Ancients

Void Staff

Rylai's Crystal Scepter

Rabadon's Deathcap

PS. You sell Doran's Ring later.

This item build is a very heavy ability power build. Stack Doran's rings, get boots, then Revolver, Deathcap. Then get a bit heavier, with Sorcerers shoes, a Will of the Ancients, Void staff, A Rylai's and end with Zhonyha's. These itemms are meant to give you a very heavy amounts of ap and damage. Will of the Ancients, mostly for spell vamp.

Noxious Blast: Small aoe damage poison.

Miasma: Small expanding aoe damage poison with a slow.

Twin Fang: Locked skillshot, timer refreshes if the target is poisoned.

Petrifying Gaze: Small aoe high damage nuke skill, stuns enemies facing you, slows away from you.

"OMG! Cass, why u no get W first?"

Because I want first blood thats why, spam Q until you turn purple in the face, you'll scare the **** out of you enemies with that damage. Also any chance you get, use twin fang.

I did edit the skills to max Twinfang first because of a suggestion, but you still can max Miasma for good damage if you're not good with twinfang. Mostly I max Q by mistake too.

VERY BRIEF EXPLANATION BELOW:

Hide in bush, use miasma, use noxious blast twice, spam twinfang, drop ulti.
Pentakill.

I prefered clarity, but ignite is useful for dishing out damage in teamfights, it singles out a target to deal more damage too, and flash is a no brainer. Clearly someone along the way, someone broke the game by giving Cassiopeia ignite.

PROS:
High Damage
No skill "wall"
Amazing teamfighter
Can 1v1
Great pusher, ganker and farmer

CONS:
You get focused alot
Limited range
Ultimate requires no margin for error to use.

Since all but one of your abilities are DoT and AoE, you can drop one, wait 3 seconds and get an assist. The damage you throw out is amazing, but because its DoT, its not as useful for the first seconds of two. In all honesty, she is probably the BEST team fighter in the game, hands down. Skill abuse is common, but not used in teamfights because of reason: waste of mana. Read the passive, go die in a fire. Miasma is the most deadly in teamfights, considering the range spreads the longer its out. Noxious blast, use it on the weakest enemies, along with Twinfang, so you can ultimate and steal, I mean legitimately obtain all the kills.

Farming, is just throw miasma near tower, wait for minions press Q. She is probably the best farmer in the game, because all but one of her main skills are DoT, meaning use one, kill them all. I've seen people use their ultimate for farming, big no no. Petrifying gaze is not a toy, it takes a real man/woman to use it right, hell even sometimes I mess up and miss it, but usually I miss the stun, never miss the shot itself.

Q: Why do you Rylai's? The HP is worthless and the passive is garbage.
A: Miasma now has a 50% slow, and your Q gives you movespeed. They aren't getting away.

Q: OMG Spell vamp is useless on aoe champs, why not get a Zhonya's instead?
A: Spell vamp for 7 seconds, giving me 300 HP per second. Zhonya's is 2 second stasis. You aren't Fiddle. And I do get Zhonya's but I get it last.

MORE FAQ ON THE WAY!