Infinite +1/+1 counters on a creatureInfinite landfall triggersInfinite self-millInfinite white manaInfinitely large creature until end of turn
How it works
Activate Serra's Sanctum by tapping it, adding at least 3.
Activate Thaumatog by sacrificing Serra's Sanctum.
Activate Tayam by paying 3 and removing three counters from creatures you control, causing you to mill three cards and return Serra's Sanctum from your graveyard to the battlefield.
When Serra's Sanctum enters, Mossborn Hydra triggers, doubling the number of +1/+1 counters on it.