Gorilla Berserkers

Trample; rampage 2 (Whenever this creature becomes blocked, it gets +2/+2 until end of turn for each creature blocking it beyond the first.)
Gorilla Berserkers can't be blocked except by three or more creatures.

Craterhoof Behemoth

Haste
When Craterhoof Behemoth enters the battlefield, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.

Rabid Wolverines

Whenever Rabid Wolverines becomes blocked by a creature, Rabid Wolverines gets +1/+1 until end of turn.

Elvish Berserker

Whenever Elvish Berserker becomes blocked, it gets +1/+1 until end of turn for each creature blocking it.

Berserk Murlodont

Whenever a Beast becomes blocked, it gets +1/+1 until end of turn for each creature blocking it.

Rabid Elephant

Whenever Rabid Elephant becomes blocked, it gets +2/+2 until end of turn for each creature blocking it.

Retaliation

Creatures you control have "Whenever this creature becomes blocked by a creature, this creature gets +1/+1 until end of turn."

Teeka's Dragon

Flying; trample; rampage 4 (Whenever this creature becomes blocked, it gets +4/+4 until end of turn for each creature blocking it beyond the first.)

Bulette

At the beginning of your end step, if a creature died this turn, put a +1/+1 counter on Bulette.

Neyith of the Dire Hunt

Whenever one or more creatures you control fight or become blocked, draw a card.
At the beginning of combat on your turn, you may pay {2}{R/G}. If you do, double target creature's power until end of turn. That creature must be blocked this combat if able. ({R/G} can be paid with either {R} or {G}.)

Copperhoof Vorrac

Copperhoof Vorrac gets +1/+1 for each untapped permanent your opponents control.

Cliffrunner Behemoth

Cliffrunner Behemoth has haste as long as you control a red permanent.
Cliffrunner Behemoth has lifelink as long as you control a white permanent.

Horrible Hordes

Rampage 1 (Whenever this creature becomes blocked, it gets +1/+1 until end of turn for each creature blocking it beyond the first.)

Aura Gnarlid

Creatures with power less than Aura Gnarlid's power can't block it.
Aura Gnarlid gets +1/+1 for each Aura on the battlefield.

Varchild's War-Riders

Cumulative upkeep—Have an opponent create a 1/1 red Survivor creature token. (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.)
Trample; rampage 1 (Whenever this creature becomes blocked, it gets +1/+1 until end of turn for each creature blocking it beyond the first.)

Fangren Firstborn

Whenever Fangren Firstborn attacks, put a +1/+1 counter on each attacking creature.

Elder Gargaroth

Vigilance, reach, trample
Whenever Elder Gargaroth attacks or blocks, choose one —
• Create a 3/3 green Beast creature token.
• You gain 3 life.
• Draw a card.

Branchsnap Lorian

Trample
Morph {G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Gnarlid Colony

Kicker {2}{G} (You may pay an additional {2}{G} as you cast this spell.)
If Gnarlid Colony was kicked, it enters the battlefield with two +1/+1 counters on it.
Each creature you control with a +1/+1 counter on it has trample.

Baloth Pup

Baloth Pup has trample as long as it has a +1/+1 counter on it.

Gang of Elk

Whenever Gang of Elk becomes blocked, it gets +2/+2 until end of turn for each creature blocking it.

Pygmy Troll

Whenever Pygmy Troll becomes blocked by a creature, Pygmy Troll gets +1/+1 until end of turn.
{G}: Regenerate Pygmy Troll.

Craw Giant

Trample
Rampage 2 (Whenever this creature becomes blocked, it gets +2/+2 until end of turn for each creature blocking it beyond the first.)

Sparring Golem

Whenever Sparring Golem becomes blocked, it gets +1/+1 until end of turn for each creature blocking it.

Viashino Weaponsmith

Whenever Viashino Weaponsmith becomes blocked by a creature, Viashino Weaponsmith gets +2/+2 until end of turn.

Balduvian War-Makers

Haste
Rampage 1 (Whenever this creature becomes blocked, it gets +1/+1 until end of turn for each creature blocking it beyond the first.)

Marhault Elsdragon

Barreling Attack

Target creature gains trample until end of turn. When that creature becomes blocked this turn, it gets +1/+1 until end of turn for each creature blocking it.

Beastmaster's Magemark

Enchant creature
Creatures you control that are enchanted get +1/+1.
Whenever a creature you control that's enchanted becomes blocked, it gets +1/+1 until end of turn for each creature blocking it.

Aerathi Berserker

Rampage 3 (Whenever this creature becomes blocked, it gets +3/+3 until end of turn for each creature blocking it beyond the first.)

Cave Tiger

Whenever Cave Tiger becomes blocked by a creature, Cave Tiger gets +1/+1 until end of turn.

Wolverine Pack

Rampage 2 (Whenever this creature becomes blocked, it gets +2/+2 until end of turn for each creature blocking it beyond the first.)