Righteous Valkyrie
An enabler and a payoff bolted onto one body, where the anthem is what gives the lifegain its teeth. The enters trigger drips life whenever another Angel or Cleric arrives, and read in isolation that is the kind of incidental gain that only pads a losing race: a few points here, a handful there, rarely amounting to a plan. What turns that drip into a clock is the threshold clause. Climb seven past where you began and the whole team swells by +2/+2, so the lifegain stops being a cushion and becomes a switch. Each Angel or Cleric that shows up then works both ends: it widens the board while feeding the counter that makes the board lethal. The tribal gate is the balancing act, since you cannot staple this onto a generic lifegain shell and expect it to fire. Only Angels and Clerics trip the trigger, which forces the whole build to commit to those two creature types before the reward pays out. Coupling a life-count anthem to a specific tribe is where the design earns its scrutiny: white has printed lifegain for decades that resolves into passive insurance and almost never into pressure. Here the number on the life pad becomes something to watch, because crossing it flips your whole team from surviving to killing.
