Nessian Boar

All creatures able to block Nessian Boar do so.
Whenever Nessian Boar becomes blocked by a creature, that creature's controller draws a card.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Flinthoof Boar

Flinthoof Boar gets +1/+1 as long as you control a Mountain.
{R}: Flinthoof Boar gains haste until end of turn. (It can attack and {T} this turn.)

Elvish Mystic

Forest

Bladetusk Boar

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Ilharg, the Raze-Boar

Trample
Whenever Ilharg, the Raze-Boar attacks, you may put a creature card from your hand onto the battlefield tapped and attacking. Return that creature to your hand at the beginning of the next end step.
When Ilharg, the Raze-Boar dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Festerhide Boar

Trample
Morbid — Festerhide Boar enters with two +1/+1 counters on it if a creature died this turn.

Bristling Boar

Bristling Boar can't be blocked by more than one creature.

Outland Boar

Outland Boar can't be blocked by creatures with power 2 or less.

Boartusk Liege

Trample
Other red creatures you control get +1/+1.
Other green creatures you control get +1/+1.

Brindle Boar

Charging War Boar

Haste (This creature can attack and {T} as soon as it comes under your control.)
As long as you control a Domri planeswalker, Charging War Boar gets +1/+1 and has trample. (It can deal excess damage to the player or planeswalker it's attacking.)

Mountain

Boar Umbra

Enchant creature
Enchanted creature gets +3/+3.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)