Summoners - Flash / Ignite work best!
Masteries - 21/0/9 For early game damage. You could also take 9/0/21.
Runes - Standard AP runes with MP marks, MP5 seals, AP Glyphs, and AP Quints (flat or per level). Or you can take full MR (38). You could also use spell vamp quints.
Items - Typically as follows: Boots-3pots, doran's ring*, hextech revolver, WOTA & sorcerers boots, and rabadons as the core build. The doran's ring is optional. Situational items are abyssal sceptre, banshee's, void staff, deathfire's grasp, zhonya's hourglass, and maybe a lich bane. If you're doing extremely well early game, rush rabadons, if you're having trouble sustaining in lane to farm, get wota. Try not to get zhonya's or lich bane unless you really need them, a Frozen Heart could easily replace zhonya's for armor with CDR.
Playstyle - Pretty much sit back and farm, harass with your 'Q' and when possible, try to follow up with your 'e' but avoid taking damage. Free harass is important on Cassiopeia. Wait for ganks when possible, Cassiopeia is best played with a CC heavy jungler like Maokai, Skarner, Udyr, or Riven. Try not to die and work for free kills, if you're not getting any kills in your lane then it may be worthwhile to try ganking your opponents' weakest lane and/or camp them. Cassiopeia relies heavily upon being fed because she does jacksquat without kills.
Counters - Pretty much every AP mid counters her through passive farm-play and the fact that she's easily out farmed if not killed since she has no escape and only one hard CC spell, her ultimate.
Who Cass Counters - lol, nobody really. Other lanes? She's a bit like LeBlanc and Sion, in the sense that she can gank pretty easily and get kills from other lanes. If you can time your ult right, you can win teamfights with ease or pick off kills with no trouble, if you miss it, you're screwed.
Cassiopeia excels at getting fed by teammates and proceeding to melt face but has trouble eating on her own when faced with competent enemies.
9/13/2011 - Corrected existing pictures and updated item buildpath picture.
9/14/2011 - Added Cassiopeia's spells picture.
5/20/2012 - Finished the guide with short and simple explanations, will add pictures later.
Edited by vVv ShowNoHope, 19 May 2012 - 07:43 AM.