'Kamigawa' cards

Whenever a player casts a spell, that player may draw a card. Whenever chaos ensues, each player may return a blue card from their graveyard to their hand.

Whenever a creature you control deals combat damage to a player, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Whenever chaos ensues, target creature can't be blocked this turn.

All creatures get +1/+1 and have haste. Whenever chaos ensues, untap all creatures that attacked this turn. If it's a main phase, there is an additional combat phase after this phase, followed by an additional main phase.

Whenever a creature leaves the battlefield, its controller draws a card. Whenever chaos ensues, return target creature you control to its owner's hand.