I’d say if you play adc, especially Ashe in this case, it will be really handy in transitioning your positioning and distancing skill to cass(Since cass E has the exact same range as ashe’s AA, both of them don’t have mobility). some tips: don’t be afraid to harass your opponent with E in level one, you would not run short on mana if you’ve got the correct rune and level up on the second wave. Enable your indicator on W, what a lot of new cass players do when they got dives is W right underneath them(which you guessed it, is quite ineffective, some champions, i.e irelia, fizz, zed will surely be positioned behind you after their dash, you could potentially utilize this to your advantage by W rearward and just a bit further from yourself, then kite them a bit). Another thing about W is: once you’ve landed your W on you opponent, don’t rush to melt his with E, observe which direction he is trying to walk out from, I’d say E once and prepare to follow up with Q. I will suggest not picking cass against midlanders which has lots of accelerating passive, Viktor is a great example, you would even have trouble farming, or irelia(natural counter to cass). As for build, Everfrost if your team lacks CC, or you want to hit consistent Rs and Ws, Mask to help you clear wave faster and that extra bit of cooldown reduction when your builds start to solidify really helps increasing your damage output, i would say that extra bit of tank and early game power spike the everfrost provides could be sacrificed for better wave clear as well as damage, but if you are sure the game is going to end fast, don’t be shy to purchase everfrost(more utility). For team fight, stay beside your ad, cass’s R is great for protecting Adc from divers, and W to counter assassins(Talon, katarina, etc.). Most importantly, don’t think about chasing enemies and EEEE all the time, be careful with positioning and enemies will come to you eventually. p.s cass does’t really need penetration, think of her more like Swain in this version, in mid to late game she is more of a mage bruiser, as long as you have enough ap, you are good to go. Core build: Liandry/everfrost - rylai - seraph embrace - death cap(normal build)/stoneplate + elixir of sorcery(cheaper, build this when the enemy team is full of divers or if your team needs another frontline).