you get a 3 mana bolt that you can then escape later, if you're casting it from your hand, and then when it hits the battlefield it certainly is quite a problem
With planeswalkers in particular, you might be less shy about taking off that final counter, since you know youll be getting it back
Paired together, though, Merlin and Madam Mim form some of the strongest combos in Rise of the Floodborn
It is one of my favourite mechanics so I cram it in where I can but in practice this is not able to compete as a stand alone module and is just there to support +1/+1 counters, infect, energy, and a few other bits and bobs
Why do we even find Bloomburrow so adorable
Between free spells, protection from your opponents, and rewarding gameplay, using cards with these mechanics will guarantee a fun time