Mirrodin Besieged

Flying Whenever a creature an opponent controls dies, you may gain 3 life. Whenever an opponent discards a card, you may gain 3 life.

At the beginning of your upkeep, you may have Cryptoplasm become a copy of another target creature, except it has this ability.

Sacrifice an artifact: Regenerate Rusted Slasher.

Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)

Defender Metalcraft — As long as you control three or more artifacts, Spire Serpent gets +2/+2 and can attack as though it didn't have defender.

Trample

{2}{B}: Dross Ripper gets +1/+1 until end of turn.

Metalcraft — Ardent Recruit gets +2/+2 as long as you control three or more artifacts.

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)

At the beginning of your upkeep, you may look at the top card of your library. You may cast it without paying its mana cost if it's an instant or s...

When Myr Sire dies, create a 1/1 colorless Myr artifact creature token.

When Viridian Emissary dies, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle your library.

Flying When Serum Raker dies, each player discards a card.

Flying When Serum Raker dies, each player discards a card.

Whenever a source deals damage to Nested Ghoul, create a 2/2 black Phyrexian Zombie creature token.

When Pierce Strider enters the battlefield, target opponent loses 3 life.

{U}: Gust-Skimmer gains flying until end of turn.

{W}: Bladed Sentinel gains vigilance until end of turn.

Vigilance Kemba's Legion can block an additional creature each combat for each Equipment attached to Kemba's Legion.

Melira's Keepers can't have counters put on it.

Metalcraft — Spiraling Duelist has double strike as long as you control three or more artifacts.