Benefactor's Draught

Untap all creatures. Until end of turn, whenever a creature an opponent controls blocks, draw a card.
Draw a card.

Bestial Fury

Enchant creature
When Bestial Fury enters, draw a card at the beginning of the next turn's upkeep.
Whenever enchanted creature becomes blocked, it gets +4/+0 and gains trample until end of turn.

Close Quarters

Whenever a creature you control becomes blocked, Close Quarters deals 1 damage to any target.

Trailblazer's Torch

When Trailblazer's Torch enters, you take the initiative.
Whenever equipped creature becomes blocked, it deals 2 damage to each creature blocking it.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Retaliation

Creatures you control have "Whenever this creature becomes blocked by a creature, this creature gets +1/+1 until end of turn."

Battle Strain

Whenever a creature blocks, Battle Strain deals 1 damage to that creature's controller.

Barreling Attack

Target creature gains trample until end of turn. When that creature becomes blocked this turn, it gets +1/+1 until end of turn for each creature blocking it.

Beastmaster's Magemark

Enchant creature
Creatures you control that are enchanted get +1/+1.
Whenever a creature you control that's enchanted becomes blocked, it gets +1/+1 until end of turn for each creature blocking it.

Gift of the Woods

Enchant creature
Whenever enchanted creature blocks or becomes blocked, it gets +0/+3 until end of turn and you gain 1 life.

Unstoppable Ash

Trample
Champion a Treefolk or Warrior (When this enters, sacrifice it unless you exile another Treefolk or Warrior you control. When this leaves the battlefield, that card returns to the battlefield.)
Whenever a creature you control becomes blocked, it gets +0/+5 until end of turn.