fling cards mtg Deck Guide: Standard Naya Fling deals damage equal to the sacrificed creatures power to any target. ≫ MTG Fling 7 combos

The latter ability is the one that Kappa Cannoneer has, and it makes it a much more powerful threat than its initial 5U cost and 4/4 statline would make it appear to be

I'm also running a few spells to steal creatures until end of turn

Try this in a lifegain-focused Commander deck, such as Karlov of the Ghost Council

Just a quick rules note: 609.3 If an effect attempts to do something impossible, it does only as much as possible

You can then tap them to take a face-down attacking creature and turn it face-up, completely skipping any cost that they might require

I may be underestimating how important Insidious Fungus is and should have it higher on the list