Familiars can be collected!

It's some set percent (15% is what I recall), I remember reading about the utility of Jr. Boogie and its friends Mr. Alli, Mutant Snail and the like over at Basil. Drip, drip, apparently Water.

Shrooms are 5% HP every 5 seconds or so, it's pretty nice. Red Snails are 10% HP every 5 seconds, but only on Vic.

I mention them particularly cause their droprates are like 50% so it's trivial to get 3 cards and have for 90 days, and some classes need HP regen more than MP.