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.)

Llanowar Tribe

Overprotect

Target creature you control gets +3/+3 and gains trample, hexproof, and indestructible until end of turn.

Predatory Impetus

Enchant creature
Enchanted creature gets +3/+3, must be blocked if able, and is goaded. (It attacks each combat if able and attacks a player other than you if able.)

Elvish Mystic

Declare Dominance

Target creature gets +3/+3 until end of turn. All creatures able to block it this turn do so.

Compelled Duel

Target creature gets +3/+3 until end of turn and must be blocked this turn if able.

Feral Contest

Put a +1/+1 counter on target creature you control. Another target creature blocks it this turn if able.

Enlarge

Target creature gets +7/+7 and gains trample until end of turn. It must be blocked this turn if able. (A creature with trample can deal excess combat damage to the player or planeswalker it's attacking.)

Savage Ventmaw

Flying
Whenever this creature attacks, add {R}{R}{R}{G}{G}{G}. Until end of turn, you don't lose this mana as steps and phases end.

Bloodscent

All creatures able to block target creature this turn do so.

Devoted Druid

{T}: Add {G}.
Put a -1/-1 counter on Devoted Druid: Untap Devoted Druid.

Fyndhorn Elves

Irresistible Prey

Target creature must be blocked this turn if able.
Draw a card.

Roar of Challenge

All creatures able to block target creature this turn do so.
Ferocious — That creature gains indestructible until end of turn if you control a creature with power 4 or greater.

You Look Upon the Tarrasque

Choose one —
• Run and Hide — Prevent all combat damage that would be dealt to you and creatures you control this turn.
• Gather Your Courage — Target creature gets +5/+5 and gains indestructible until end of turn. All creatures your opponents control able to block that creature this turn do so.

Lure

Enchant creature
All creatures able to block enchanted creature do so.

Goblin Anarchomancer

Each spell you cast that's red or green costs {1} less to cast.

Anzrag, the Quake-Mole

Whenever Anzrag, the Quake-Mole becomes blocked, untap each creature you control. After this phase, there is an additional combat phase.
{3}{R}{R}{G}{G}: Anzrag must be blocked each combat this turn if able.

Priest of Titania

{T}: Add {G} for each Elf on the battlefield.

General Marhault Elsdragon

Whenever a creature you control becomes blocked, it gets +3/+3 until end of turn for each creature blocking it.

Anara, Wolvid Familiar

During your turn, commanders you control have indestructible. (Effects that say "destroy" don't destroy them. A creature with indestructible can't be destroyed by damage.)
Partner (You can have two commanders if both have partner.)

Llanowar Loamspeaker

{T}: Add one mana of any color.
{T}: Target land you control becomes a 3/3 Elemental creature with haste until end of turn. It's still a land. Activate only as a sorcery.