Now this is VERY VERY similar to what I use nowadays (u changed your build, havent you?:)) I just would make few changes, dont buy swiftness boots but buy sorcerers shoes, for those reasons = along with magic pene runes, it gives you about 30 m.pen. which makes most of enemies very vulnerable against you. plus u dont need speed cause your "Q" ability makes you faster when u poison a champion. I still leave it shurelia item and buy spell vamp instead earlier, i also leave yout zhonya hours.

for the comment above, yes cassiopeia NEEDS CDR and MP regen, she spams spells and CDR is very usefull, especially for Q and W ability and her ultimate. She doesnt need much mana, since her passive reduces the cost, so if regen is OK, then u are fine.

Death fire graps is also great item for her, it is built from maki pedant, which is best for early game as a 1st item along with 2 health pots. later you should buy kaige pick so it generates gold and dont buy deathfire grasp yet, just profit from kaige´s. Buy deathfire when u face enemy with a lot of HP´s or magic resist, it is the initiating move of your combo, you instantly take 30-40% of their HP and then you start dealing DoT´s, possibly stun with your ultimate, and bang, you walk away as a serpent queen covered in shining fame :)))
thus, this build is BEST on mobafire for cass, much better than the highest rated one, you deserve better rating dude :))

I find that without a Meki Pendant (or mana seals + glyphs), Cassiopeia becomes fairly useless, pretty fast. Meki Pendant allows you to build (apart from chalice of the harmony), Fiendish Codex or Tear of the Goddess. I have tried building Tear many times, and I eventually realized the extra mana was worthless, and thus the whole item is a waste (besides, AP from Archangel's Staff would be bought much later, or would delay the survivability Rylai's Crystal Scepter provides).

Therefore, Fiendish Codex (sometimes I will purchase only a Meki Pendant and keep it for the entire game) is the most logical choice.

It provides:

10MP5
15% cooldown reduction
Ability Power
Single Target Nuke (scales with AP, will do damage equal to 50% of target's health at the end of build). Squishy = DEAD


Re: Cooldown reduction
I have tried both with 0 cooldown reduction and 40%. There is a noticable difference in Cassiopeia's damage output in teamfights with no cooldown reduction. Noxious Blast (hits hard, always) has 3 second cooldown normally. Ulti is a great utility in teamfights and 1v1 and has a long cooldown. misma has 9 second cooldown, 7 second duration, 2 second slow. Using this more than once in a fight is useful. 40% cooldown means Miasma its on a 5.5 second cooldown.

Twin Fang
Still has a cooldown of 0.5 seconds, u must also keep up poison, which, without cooldown reduction is much harder, since your spammable poison has a 3 second cooldown (applying posion for 3 seconds), with a cast time, and delay time to explode. 40% cooldown reduction brings Twin Fang to a 0.3 second cooldown and is instrumental in keeping your nuke available through other abilities (btw, it still has a casting time, and ofc targeting delay).

I agree that Cassiopeia without cooldown reduction is viable, but it is suboptimal when many fights (mostly non-5v5) after everyone has completed 4/5/6 items, end very fast.

I'd like to hear your thoughts on why Cassiopeia does not need any MP5, at all

Deathfire grasp¿?
Cassiopeia with mp5 and CDR? are you serious?
U can spam 2 of you 3 abilities... and never oom!

Seems pretty nice.

thanks for the comment, I have <50 games with Cass so I look forward to hearing from more cass players.

on Teleport:

I play low elo ranked, and I guess the audience for these guides is not high elo / pros. That said, I chose teleport because of its awesome tower saving capability, fast re-laning (goes well with my cheap, lane oriented first 4 shops), and pushing opportunities.

My teams often lack push power or are weak in defense somewhere. So, yea I often find I play a hybrid support with this setup, but if it helps win, i dont mind :)

oh, and from what i've played - ward + teleport + ward + spam spam spam +shurelyas + boots of swiftness = easy tower + fast farm, when the other team is busy elsewhere :D


edit: added my comments on Teleport in the summoner spells section

Cassiopeia is my main, so i have a LOT of experiences with this weak underpowered champion that none plays. I like some things about your build, its completely different than my build (i will post it here soon) But I like shurelia reverie, since it gives u mp regen and hp regen and cd reduction. But i think you lack some Ability power and since u got HP regen, u no longer need spell vamp, thats my opinion, cassiopeia is not supposed to stay in fight for a long time, shes an "AoE DoT Nuker". shes extremely fragile and squishy, so best way to play her is to deal DoTs, harass and strike with her ulti in mass fights and then escape with remaining health. Also i dont understand why did you go for Teleport? I think its for support champions, i couldnt find it useful for cass.neverthelees, nice build and explanations but i think you need to change items and order and summoner spells.

Comments are appreciated :)