As someone who already tried deck’s around kara’s BBS, I recommend snow chaser. Having them go back and forth, from your hand to the board, makes sure you have something that can benefit from the BBS and if you don’t need them you can allways replace them.
If you want to go full meme, you can add firestarter. He’s hard to keep on board, but I got some sweet wins comboed with lightning blitz.
Owlbeast sage works well if you go the arcanyst route. But it does not particularly synergize with the BBS. (+2 health per use is still great)
Sanguinar is another 4 drop that could be considered. A lot of time you just won’t have enough mana to use the BBS AND put minions down. It also helps when you want to chain cryptomancers.
Edit This is the deck I am currently running with kara in diamond. The idea was to have a smooth curve with minions that can benefit from kara’s BBS.