Xantcha, Sleeper Agent

Xantcha enters under the control of an opponent of your choice.
Xantcha attacks each combat if able and can't attack its owner or planeswalkers its owner controls.
{3}: Xantcha's controller loses 2 life and you draw a card. Any player may activate this ability.

Manabarbs

Whenever a player taps a land for mana, this enchantment deals 1 damage to that player.

Mana Flare

Whenever a player taps a land for mana, that player adds one mana of any type that land produced.