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

Trample
Champion an Elemental (When this enters the battlefield, sacrifice it unless you exile another Elemental you control. When this leaves the battlefield, that card returns to the battlefield.)

Trample
When Phyrexian Dreadnought enters the battlefield, sacrifice it unless you sacrifice any number of creatures with total power 12 or greater.

Trample
Polar Kraken enters the battlefield tapped.
Cumulative upkeep—Sacrifice a land. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

This spell costs less to cast for each creature your opponents control.
When Primeval Protector enters the battlefield, put a +1/+1 counter on each other creature you control.

Protection from everything
If Progenitus would be put into a graveyard from anywhere, reveal Progenitus and shuffle it into its owner's library instead.

Fading 2 (This creature enters the battlefield with two fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Skyshroud Behemoth enters the battlefield tapped.

Annihilator 1 (Whenever this creature attacks, defending player sacrifices a permanent.)
: Create two 0/1 colorless Eldrazi Spawn creature tokens. They have "Sacrifice this creature: Add ."
: Cast any number of Eldrazi spells from among cards you own outside the game without paying their mana costs.

When Sundering Titan enters the battlefield or leaves the battlefield, choose a land of each basic land type, then destroy those lands.

Flying
Champion an Elemental (When this enters the battlefield, sacrifice it unless you exile another Elemental you control. When this leaves the battlefield, that card returns to the battlefield.)

Eminence — As long as The Ur-Dragon is in the command zone or on the battlefield, other Dragon spells you cast cost less to cast.
Flying
Whenever one or more Dragons you control attack, draw that many cards, then you may put a permanent card from your hand onto the battlefield.

Trample
Cycling (, Discard this card: Draw a card.)
When you cycle Titanoth Rex, put a trample counter on target creature you control.

Defender
: Exchange target opponent's life total with Tree of Perdition's toughness.

Defender
: Exchange your life total with Tree of Redemption's toughness.

When you cast this spell, exile two target permanents.
Indestructible
Whenever Ulamog, the Ceaseless Hunger attacks, defending player exiles the top twenty cards of their library.

When you cast this spell, destroy target permanent.
Indestructible
Annihilator 4 (Whenever this creature attacks, defending player sacrifices four permanents.)
When Ulamog, the Infinite Gyre is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.

Your opponents can't cast spells with even converted mana costs. (Zero is even.)
Your opponents can't block with creatures with even converted mana costs.

Flying, intimidate, trample (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a player loses the game, put thirteen +1/+1 counters on Withengar Unbound.

Trample
When Worldspine Wurm dies, create three 5/5 green Wurm creature tokens with trample.
When Worldspine Wurm is put into a graveyard from anywhere, shuffle it into its owner's library.