If an effect instructs you to “double” a creature’s power, that creature gets +X/+0, where X is its power as that effect begins to apply. Similarly, a creature whose toughness is doubled gets +0/+X, where X is its toughness as the effect begins to apply.
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Create a 5/5 green Elephant creature token.
III — Double the power and toughness of each creature you control until end of turn.
