Nemesis Mask

All creatures able to block equipped creature do so.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Battle Strain

Whenever a creature blocks, Battle Strain deals 1 damage to that creature's controller.

Inferno Hellion

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
At the beginning of each end step, if Inferno Hellion attacked or blocked this turn, its owner shuffles it into their library.

Grand Melee

All creatures attack each combat if able.
All creatures block each combat if able.

Melee

Cast this spell only during your turn and only during combat before blockers are declared.
You choose which creatures block this combat and how those creatures block.
Whenever a creature attacks and isn't blocked this combat, untap it and remove it from combat.

Impetuous Devils

Trample, haste
When Impetuous Devils attacks, up to one target creature defending player controls blocks it this combat if able.
At the beginning of the end step, sacrifice Impetuous Devils.

Caves of Chaos Adventurer

Trample
When Caves of Chaos Adventurer enters, you take the initiative.
Whenever Caves of Chaos Adventurer attacks, exile the top card of your library. If you've completed a dungeon, you may play that card this turn without paying its mana cost. Otherwise, you may play that card this turn.

Fire Juggler

Whenever Fire Juggler becomes blocked, clash with an opponent. If you win, Fire Juggler deals 4 damage to each creature blocking it. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Heat Stroke

At end of combat, destroy each creature that blocked or was blocked this turn.

Magnetic Web

If a creature with a magnet counter on it attacks, all creatures with magnet counters on them attack if able.
Whenever a creature with a magnet counter on it attacks, all creatures with magnet counters on them block that creature this turn if able.
{1}, {T}: Put a magnet counter on target creature.

Coveted Jewel

When Coveted Jewel enters, draw three cards.
{T}: Add three mana of any one color.
Whenever one or more creatures an opponent controls attack you and aren't blocked, that player draws three cards and gains control of Coveted Jewel. Untap it.

Blood Frenzy

Cast this spell only before the combat damage step.
Target attacking or blocking creature gets +4/+0 until end of turn. Destroy that creature at the beginning of the next end step.

Mountain

Hinterland Scourge

Hinterland Scourge must be blocked if able.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform Hinterland Scourge.

Hinterland Hermit

At the beginning of each upkeep, if no spells were cast last turn, transform Hinterland Hermit.

Hinterland Hermit // Hinterland Scourge

Norin, Swift Survivalist

Norin, Swift Survivalist can't block.
Whenever a creature you control becomes blocked, you may exile it. You may play that card from exile this turn.

Charming Scoundrel

Haste
When Charming Scoundrel enters, choose one —
• Discard a card, then draw a card.
• Create a Treasure token.
• Create a Wicked Role token attached to target creature you control.

Grappling Hook

Equipped creature has double strike.
Whenever equipped creature attacks, you may have target creature block it this turn if able.
Equip {4}

Laccolith Rig

Enchant creature
Whenever enchanted creature becomes blocked, you may have it deal damage equal to its power to target creature. If you do, the first creature assigns no combat damage this turn.

Dead-Iron Sledge

Whenever equipped creature blocks or becomes blocked by a creature, destroy both creatures.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Heat of Battle

Whenever a creature blocks, Heat of Battle deals 1 damage to that creature's controller.

No Quarter

Whenever a creature becomes blocked by a creature with lesser power, destroy the blocking creature.
Whenever a creature blocks a creature with lesser power, destroy the attacking creature.

False Orders

Cast this spell only during the declare blockers step.
Remove target creature defending player controls from combat. Creatures it was blocking that had become blocked by only that creature this combat become unblocked. You may have it block an attacking creature of your choice.

Inescapable Brute

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Inescapable Brute must be blocked if able.

Mark for Death

Target creature an opponent controls blocks this turn if able. Untap that creature. Other creatures that player controls can't block this turn.

Kami of Celebration

Whenever a modified creature you control attacks, exile the top card of your library. You may play that card this turn. (Equipment, Auras you control, and counters are modifications.)
Whenever you cast a spell from exile, put a +1/+1 counter on target creature you control.

Close Quarters

Whenever a creature you control becomes blocked, Close Quarters deals 1 damage to any target.

Berserker's Frenzy

Cast this spell only before combat or during combat before blockers are declared.
Roll two d20 and ignore the lower roll.
1—14 | Choose any number of creatures. They block this turn if able.
15—20 | You choose which creatures block this turn and how those creatures block.

Defiler of Instinct

First strike
As an additional cost to cast red permanent spells, you may pay 2 life. Those spells cost {R} less to cast if you paid life this way. This effect reduces only the amount of red mana you pay.
Whenever you cast a red permanent spell, Defiler of Instinct deals 1 damage to any target.

Infiltration Lens

Whenever equipped creature becomes blocked by a creature, you may draw two cards.
Equip {1}

Bumper Cars

Visit — Target creature must be blocked this turn if able.

Guild Artisan

Commander creatures you own have "Whenever this creature attacks a player, if no opponent has more life than that player, you create two Treasure tokens." (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Goblin Fire Fiend

Haste
Goblin Fire Fiend must be blocked if able.
{R}: Goblin Fire Fiend gets +1/+0 until end of turn.

Academic Dispute

Target creature blocks this turn if able. You may have it gain reach until end of turn.
Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Invasion Plans

All creatures block each combat if able.
The attacking player chooses how each creature blocks each combat.