The Aching of the Spirit Tree

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Target land becomes a Swamp.
II — Creatures your opponents control get -2/-2 until end of turn.
III — Each player sacrifices half the creatures, then lands, then planeswalkers they control. Round up each time. You gain life equal to the number of permanents sacrificed this way.