Life Doubler

Permanents with a replacement effect reading roughly "if you would gain life, you gain twice that much life instead," multiplying every lifegain event. Rhox Faithmender, Boon Reflection, and Alhammarret's Archive are the canonical pieces, and they stack multiplicatively when several are in play. Distinct from lifegain.lifegain_source, which generates the gain events in the first place, and from lifegain.lifegain_payoff, which triggers off gain events without changing their size. Also distinct from lifegain.drain, which moves life between players rather than amplifying it.