Aether Sting

Whenever an opponent casts a creature spell, this enchantment deals 1 damage to that player.

Blazing Volley

Blazing Volley deals 1 damage to each creature your opponents control.

Aggravate

Aggravate deals 1 damage to each creature target player controls. Each creature dealt damage this way attacks this turn if able.

Ashmouth Hound

Whenever this creature blocks or becomes blocked by a creature, this creature deals 1 damage to that creature.

Barrage of Boulders

Barrage of Boulders deals 1 damage to each creature you don't control.
Ferocious — If you control a creature with power 4 or greater, creatures can't block this turn.

Barbed Wire

At the beginning of each player's upkeep, this artifact deals 1 damage to that player.
{2}: Prevent the next 1 damage that would be dealt by this artifact this turn.

Blisterspit Gremlin

{1}, {T}: This creature deals 1 damage to each opponent.
Whenever you cast a noncreature spell, untap this creature.

Battle Strain

Whenever a creature blocks, this enchantment deals 1 damage to that creature's controller.

Barbed Field

Enchant land
Enchanted land has "{T}: This land deals 1 damage to any target."

Ghyrson Starn, Kelermorph

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Three Autostubs — Whenever another source you control deals exactly 1 damage to a permanent or player, Ghyrson Starn deals 2 damage to that permanent or player.