Skinrender

When Skinrender enters, put three -1/-1 counters on target creature.

Fume Spitter

Sacrifice Fume Spitter: Put a -1/-1 counter on target creature.

Swamp

Copper Myr

Vector Asp

{B}: Vector Asp gains infect until end of turn. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Grafted Exoskeleton

Equipped creature gets +2/+2 and has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Grafted Exoskeleton becomes unattached from a permanent, sacrifice that permanent.
Equip {2}

Strider Harness

Equipped creature gets +1/+1 and has haste.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Ezuri's Archers

Reach (This creature can block creatures with flying.)
Whenever Ezuri's Archers blocks a creature with flying, Ezuri's Archers gets +3/+0 until end of turn.

Horizon Spellbomb

{2}, {T}, Sacrifice Horizon Spellbomb: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
When Horizon Spellbomb is put into a graveyard from the battlefield, you may pay {G}. If you do, draw a card.

Tangle Angler

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{G}: Target creature blocks Tangle Angler this turn if able.

Nim Deathmantle

Equipped creature gets +2/+2, has intimidate, and is a black Zombie. (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a nontoken creature is put into your graveyard from the battlefield, you may pay {4}. If you do, return that card to the battlefield and attach Nim Deathmantle to it.
Equip {4}

Putrefax

Trample, haste
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
At the beginning of the end step, sacrifice Putrefax.

Grasp of Darkness

Target creature gets -4/-4 until end of turn.

Corpse Cur

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Corpse Cur enters, you may return target creature card with infect from your graveyard to your hand.

Relic Putrescence

Enchant artifact
Whenever enchanted artifact becomes tapped, its controller gets a poison counter.

Carnifex Demon

Flying
Carnifex Demon enters with two -1/-1 counters on it.
{B}, Remove a -1/-1 counter from Carnifex Demon: Put a -1/-1 counter on each other creature.

Myr Battlesphere

When Myr Battlesphere enters, create four 1/1 colorless Myr artifact creature tokens.
Whenever Myr Battlesphere attacks, you may tap X untapped Myr you control. If you do, Myr Battlesphere gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.

Cystbearer

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Infiltration Lens

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

Forest

Plague Stinger

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Tel-Jilad Fallen

Protection from artifacts
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Slice in Twain

Destroy target artifact or enchantment.
Draw a card.

Tainted Strike

Target creature gets +1/+0 and gains infect until end of turn. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Untamed Might

Target creature gets +X/+X until end of turn.

Ichorclaw Myr

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Ichorclaw Myr becomes blocked, it gets +2/+2 until end of turn.