Plague Myr

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{T}: Add {C}.

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.

Priests of Norn

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

Silver Myr

Viral Drake

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{3}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Drafna, Founder of Lat-Nam

{1}{U}: Return target artifact you control to its owner's hand.
{3}, {T}: Copy target artifact spell you control. (The copy becomes a token.)

Blighted Agent

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Blighted Agent can't be blocked.

Gold Myr

Ayesha Tanaka, Armorer

Whenever Ayesha Tanaka, Armorer attacks, look at the top four cards of your library. You may put any number of artifact cards with mana value less than or equal to Ayesha's power from among them onto the battlefield tapped. Put the rest on the bottom of your library in a random order.
Ayesha can't be blocked as long as defending player controls three or more artifacts.