Firesong and Sunspeaker

Red instant and sorcery spells you control have lifelink.
Whenever a white instant or sorcery spell causes you to gain life, Firesong and Sunspeaker deals 3 damage to target creature or player.

Spear Spewer

Defender
{T}: Spear Spewer deals 1 damage to each player.

Rem Karolus, Stalwart Slayer

Flying, haste
If a spell would deal damage to you or another permanent you control, prevent that damage.
If a spell would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 1 instead.

Acidic Soil

Acidic Soil deals damage to each player equal to the number of lands they control.

Flame Rift

Flame Rift deals 4 damage to each player.

Mana Clash

You and target opponent each flip a coin. Mana Clash deals 1 damage to each player whose coin comes up tails. Repeat this process until both players' coins come up heads on the same flip.

Heartless Hidetsugu

{T}: Heartless Hidetsugu deals damage to each player equal to half that player's life total, rounded down.