{T}: Put a flood counter on target land.

Aqua Elemental gets +1/+1 for each land your opponents control with a flood counter on it

{3}{U}: Transform Aqua Elemental. Activate only as a sorcery.

Lands with flood counters on them are islands.

{2}{U}, {T}: Each opponent chooses a land they control and puts a flood counter on it

{4}{U}, {T}: Draw a card for each island target opponent controls