This was originally going to be a top 10 list, but I simply couldnt narrow it down
Hinterland Sanctifier Hinterland Sanctifier has a good half of a Soul Sister ability to gain life, and combined with an all important two points of toughness, land this Sanctifier as an excellent option if you want to trigger lifegain as many times as possible
Removing creatures from combat won't reduce the number of rad counters they get
Super Rare (SR): Powerful cards with unique effects, making them highly sought after
Leonardo's last ability triggers just once for each life-gaining event, whether it's 1 life from Illegitimate Business or 3 life from Guac & Marshmallow Pizza
Heliod, Sun-Crowned Even if youre not trying to go infinite with the Walking Ballista combo, if you care about lifegain, you want Heliod, Sun-Crowned in your deck, or in the command zone as one of the best mono-white commanders