Oberon, Nature's Guardian

Partner with Titania, Razor Pixie (When this
creature enters the battlefield, target player may put
Titania into their hand from their library, then
shuffle.)
Creature tokens you control get +1/+0 and have vigilance and "Whenever this creature attacks,
you gain 1 life."
{x}{x}{1}{g/w}, {t}: Populate X times. You gain half X
life. Round up.