Each rad counter represents a life point and a milled non-land card, plus however many milled land cards are in between
If you combine Heliod and Spike Feeder with Conclave Mentor, you can make one creature infinitely large, since you get an extra counter with each Heliod trigger
Ive managed to select the best of 289 total cards, considering aspects like Constructed playability, Commander playability, and financial value
Tournament legality fuels steady demand among competitive players
This fits with the changing design principles and general power creep of MTG
The restriction of only one target per turn is somewhat diminished by the fact that this card enables you to play green, and cards like Eternal Witness or Regrowth are very welcome recursion enablers in a deck that's already grindy by itself