Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards. (They put the top three cards of their library into their graveyard.)

Fastbond

You may play any number of lands on each of your turns.
Whenever you play a land, if it wasn't the first land you played this turn, this enchantment deals 1 damage to you.

Crop Rotation

As an additional cost to cast this spell, sacrifice a land.
Search your library for a land card, put that card onto the battlefield, then shuffle.

Seedtime

Cast this spell only during your turn.
Take an extra turn after this one if an opponent cast a blue spell this turn.

Oboro, Palace in the Clouds

{T}: Add {U}.
{1}: Return Oboro to its owner's hand.