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.)

Prickly Boggart

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

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.)

Barony Vampire

Chromatic Star

{1}, {T}, Sacrifice this artifact: Add one mana of any color.
When this artifact is put into a graveyard from the battlefield, draw a card.

Ichor Wellspring

When this artifact enters or is put into a graveyard from the battlefield, draw a card.

Swamp

Virulent Wound

Put a -1/-1 counter on target creature. When that creature dies this turn, its controller gets a poison counter.

Flensermite

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Traveler's Amulet

{1}, Sacrifice this artifact: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Shambling Ghast

When this creature dies, choose one —
• Target creature an opponent controls gets -1/-1 until end of turn.
• Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Relic Putrescence

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

Swamp Mosquito

Flying
Whenever this creature attacks and isn't blocked, defending player gets a poison counter. (A player with ten or more poison counters loses the game.)

Phyresis

Enchant creature
Enchanted creature has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)