How should I build Cass in Twisted Treeline (3v3)?

I played a match with some friends recently and we had 6, so we decided to play 3v3. I have seen several builds for Cass and she is my favorite champion so far, but I didn't build the best in a 3v3 situation. I know that the build depends a lot on what your enemy team is and how they build, but perhaps some pointers here and there would help for next time so I don't embarrass myself in front of all my work buddies?

I'll let other people tell you how to build her but in my honest opinion, in 3's, Cass can only be built according to what the enemy team has.

IE items like Void Staff, Abyssal Scepter and Zhonya's Hourglass comes in mind. You'll have to balance out the items depending if the other team is tanky, mostly AD, mostly AP or hybrid.

The TT meta is very aggressive towards squishy casters, specially those with less CC. Build normally if their team is also "normal" (tank, caster, carry), MR if they're imba towards AP (like those weird katarina-into-akali teams) or try stacking a bit of hp versus too tanky teams. Remember that the tanky teams usually have people roaming a lot, so ward mid and NEVER facecheck brushes. Use your poke to your advantage, that movement speed goes a ways

You've got to get powerful very fast in TT. Taking the time to build mana base, THEN working on your ap, doesnt work. In 5v5, it will take 15 minutes to get out of lane phase. in TT, after 15 minutes, the game may very well already be decided with three to four turrets down and a crazy imbalance of k/d. I've found most success on squishy casters in rushing athene's unholy grail now, then moving onto an ROA. As a squishy caster, its definitely important to build for survivability if you have no innate escapes or serious stuns. a very good Ziggs can probably just go balls to the wall AP because he does have some tricks up his sleeve, and Veigar can probably just go ap as well because of his aoe stun, and so can Fizz because of his insane mobility. but there really arent that many squishy characters that can just do ap. ROA and Zhyonas are a MUST for TT, and a Frozen Heart is also highly recommended against any AD based character. I know that it doesnt give AP, but it DOES increase your DPS by a **** ton, because of the 20% CDR. It doesnt sound like much, but it makes a HUGE difference. Abyssal Scepter is highly recommended, and i hardly ever get anything except merc treads unless im going Mordekaiser, but i've built him from the ground up and my playstyle with him is totally unique, so that may not count. Lich Bane may or may not be useful depending on the character.

I usually get rod of ages, a few doran's rings, sorcerer's shoes, rabadon's deathcap, zhonya's hourglass, abyssal scepter, void staff if they have a lot of mr.

You shouldn't play Cassiopeia on 3vs3. 3vs3 is in control of hypercarries which build tanky aswell, like Jax. Yorick is a great champ for a 2vs1 bot lane and generally 2 hypercarries are better than 1. If you fill that finally with Lee Sin as a jungler you have a great team vs teams which don't jungle, you will easily outscale them. And I think at your level this will happen most of the time.

More infos you can find here: http://www.lolpro.com/guides/game-play/257-gameplay-guide-twisted-treeline

Disagreed. Sigh, this rep monster above me.... Says anything just to get rep.

NEVER get a jungler in TT. Unless the enemy team has a stupid comp and you can 2v1 them easily. Yorick is not good 2v1 compared to other champions. There are not many camps and great distances between the camps. If you get all hypercarries, they can counter you if they have ONE tank. That is all they need. Anyway, you should get a sustain AP carry going top. If you want Cassiopeia, get Will of the Ancients. Fiddlesticks is an extremely good champion because of huge damage and sustain.

Get Zhonya's Hourglass against AD and Abyssal Scepter against AP. Get some health items with either RoA or Rylai's.

So, you disagree with the 1. rated 3vs3 player of th world, Only Jaximus.

You never played 3vs3 on competetive scene, right? So how you can know about it?

A 3vs3 tier list: www.reignofgaming.net/tier-lists/threes-tier-list/20089-only-jaximus-3v3-tier-list-ranked-hecarim-patch

Just because it works for HIM, does not mean it works for EVERYONE. If you go and jungle, your bot lane will get CRUSHED. Plain and simple. Because most people are not used to doing a 2v1. Now, if you want to jungle to go along WITH a lane, be my guest. I push creep waves so fast solo top as Mord, i HAVE to go in and clear jungle between every wave to keep my CS and lvling up. We have had this discussion before. Neil Pert is considered to be the best drummer in the world by many people, but will YOU try to play three different drumkits at the same time while your platform is rotating upside down above a crowd? No. Works for him, not for you. Only Jaximus can jungle in 3s because his solo bot partner is USED to it, and can hold his own. Trying to jungle in soloq DOES NOT WORK because, hey, if you're asking for advice on MobaFire, you aren't in the pro scene. Even if you were a pro, assuming your partners are pro will lose the game for you, because you would be asking too much.

Drop the Jungle 3s, dude.

So, you shouldn't jungle in the 5vs5 because people in solo queue can't solo top since they could meat 2 champs and die instantly? It is basically the same. Solo bot in 3vs3 is the same as solo top in 5vs5. Except that in 3vs3 the lane support from junglers is higher and this way to solo vs 2 is easier.