*UpDated 13-5-2011

Hey all, its my first guide and sorry for my wrong english, Im just learning this language in a little amount. Many my friends told me Cassiopeia is hard to play,dont have a dmg and its waste points, but i dont think so. As Cassiopeia its possible to do IK or u can burst enemies so much. Its my favorite hero because of a few reasons (Ultimate skill, gamestyle....)


STORY:
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While her sister Katarina has always been the most celebrated member of the household, the Du Couteau family has a long history of service to Noxus. It has often been said that no soldier has ever been as fortunate as General Du Couteau to have been graced with daughters. His youngest, Cassiopeia - despite lacking her sister's killer instincts - was equally renowned in court for her stately character and elegance. Cunning as she was beautiful, the temptress could never be found far from the arm of any foreign dignitary, her wiles prying secrets from the lips of even the most wary attach©. With the Noxian barbarian pacification campaign having ground to a standstill, Cassiopeia had set her sights on a diplomat from a tribe of the Freljord region. Thinking him an easy mark, the scheming seductress set about beguiling him. He refused to confide in her, however, until she swore an oath of secrecy upon his sword - a strange weapon with a serpentine curve to the blade.

Once her tryst was over, Cassiopeia provisioned her father with information regarding the barbarian resistance. As she divulged this intelligence, a wave of revulsion washed over her. She screamed in agony as her silky skin hardened to scales, her lustrous hair thickened to leather, and her manicured fingernails sharpened to claws. Dazed, she fell upon a group of horrified servants, rending them limb from limb in a heartbeat. When it was over the blood soaked figure was no longer the ravishing jewel of the Noxian court, but a horror trapped somewhere between woman and serpent. Unable to serve in her traditional capacity, Cassiopeia departed for the League, continuing her service to Noxus on the Fields of Justice.

'Though she may have appeared the innocent flower, she was the serpent under it.' - Katarina, the Sinister Blade

PLEASE DONT RATE IF U DIDNT TRY THIS BUILD

Pros:
+Excellent harasser
+Good passive skill
+Poison does tons of damage
+Does a good amount of damage (Late game can be a drag)
+A good carry if played right

Cons:
-Squishy
-Expensive

- why this one ? Much people says no, but i think its very usefull (30%hp with one button) in 1v1 (face to face) and in teamfighs too (u can kill tank so fast)
- just a once thing... survivality
- this item is good because of his magic pene and magic resist (passive self and aura)

*
-I know not all ap heros ar good with spellvamp,
-second rabadon is good choice for + 155ap and there is nothing like that or with more ap...i know, ull appeal with Archangel staff, but i think its not good choice for staff bonus(3% mana is converted to ap), ye it would be good if u ar going to 5x Archangel staff + 1x Rabadon on Karthus with 1300ap, but here is one.. or maybe a few difs... Cass dont need much mana like Karthus or another ap(mage) hero.
-Next one is spellvamp - i think spellvamp isnt required for Cass because almost everytime, if u ar not on cooldown ulti, enemy player is running away or he try to CC/kitty u and there is once thing what u should do and its - go back... At another side, if enemy player is trying to kill u and u ar not on cooldown ulti he will die so fast, he cant do anything...
-And what about lich bane ? , this item is useful maybe in early game for Unique bonus but stats? Man.. rally (+350 Mana +80 Ability Power +30 Magic Resist +7% Movement Speed) is ****, maybe +7% movement is something about discusion but other stats ? sorry but its not good choice for me...

U can useorthere is only once dif and its: withu can instantly catch enemy.
Withu must follow enemy and spamand- u can slow and kill the enemy easier...
- Its possuble to use ignite for max ur dps but im up for exhaust because Cassiopeia dmg is sufficient to kill enemy in short time...

Abilities

-Noxious Blast - Cassiopeia blasts an area with a delayed high damage poison, granting her increased Movement Speed if she hits a champion.
Cassiopeia blasts an area with a delayed high damaging poison, dealing 75/115/155/195/235 (+0.9) magic damage over 3/3/3/3/3 seconds and granting her 15/17.5/20/22.5/25% Movement Speed for 3/3/3/3/3 seconds if she hits a champion.
Cost
35/45/55/65/75 Mana
Range
850
-Miasma - Cassiopeia releases a cloud of poison, lightly damaging and slowing any enemy that happens to pass through it.
Cassiopeia releases a growing cloud of poison that lasts for 7/7/7/7/7 seconds. Any enemy that passes through it is poisoned for 2/2/2/2/2 seconds, dealing 25/35/45/55/65 (+0.15) magic damage each second and slowing them by 15/20/25/30/35%. Continual exposure renews this poison.
Cost
70/80/90/100/110 Mana
Range
850
-Twin Fang - Cassiopeia lets loose a damaging attack at her target. If the target is poisoned the cooldown of this spell is refreshed.
Cassiopeia deals 60/95/130/165/200 (+0.55) magic damage to her target. If the target is poisoned then Twin Fang's cooldown is reduced to 0.5/0.5/0.5/0.5/0.5 seconds.
Cost
50/60/70/80/90 Mana
Range
700
-Petrifying Gaze - Cassiopeia releases a swirl of magical energy from her eyes, stunning any enemies in front of her that are facing her and slowing any others with their back turned.
Cassiopeia deals 200/325/450 (+0.6) magic damage to all enemies in front of her. Enemies facing her are stunned for 2/2/2 seconds while enemies facing away are slowed by 60/60/60%.
Cost
120/160/200 Mana
Range
750
-Deadly Cadence - After casting a spell any subsequent spellcasts will cost 10% less for 5 seconds. This ability stacks up to 5 times.


Tips:

-Use Twin Fang on poisoned stationary targets like monsters and units stunned by her Petrifying Gaze for maximum damage.
-Lead your enemy when targeting with Noxious Blast to ensure the hit.
-Don't hesitate to rapidly cast your spells since Deadly Cadence makes each additional cast cheaper.


Almost every time if im face to face with someone i use Qthen Wfor slow enemy, 2x E, after this u can use urand do again this rotation.

If target is not runing out of u then use Q W RE Q E E

WARNING: Dont waste ur ulti if target isnt face to face to u.