Phyrexian Snowcrusher

Phyrexian Snowcrusher attacks each combat if able.
{1}{S}: Phyrexian Snowcrusher gets +1/+0 until end of turn. ({S} can be paid with one mana from a snow source.)

Juggernaut

This creature attacks each combat if able.
This creature can't be blocked by Walls.

Extruder

Echo {4} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
Sacrifice an artifact: Put a +1/+1 counter on target creature.

Galvanic Juggernaut

Galvanic Juggernaut attacks each combat if able.
Galvanic Juggernaut doesn't untap during your untap step.
Whenever another creature dies, untap Galvanic Juggernaut.

Urza's Engine

Trample
{3}: Urza's Engine gains banding until end of turn. (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding you control are blocking or being blocked by a creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)
{3}: Attacking creatures banded with Urza's Engine gain trample until end of turn.

Keldon Battlewagon

Trample
Keldon Battlewagon can't block.
When Keldon Battlewagon attacks, sacrifice it at end of combat.
Tap an untapped creature you control: Keldon Battlewagon gets +X/+0 until end of turn, where X is the power of the creature tapped this way.

Barricade Breaker

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Barricade Breaker attacks each combat if able.

Energizer

{2}, {T}: Put a +1/+1 counter on Energizer.

Otarian Juggernaut

Otarian Juggernaut can't be blocked by Walls.
Threshold — As long as seven or more cards are in your graveyard, Otarian Juggernaut gets +3/+0 and attacks each combat if able.

Phyrexian Juggernaut

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Phyrexian Juggernaut attacks each combat if able.

Darksteel Juggernaut

Indestructible
Darksteel Juggernaut's power and toughness are each equal to the number of artifacts you control.
Darksteel Juggernaut attacks each combat if able.

Arcbound Crusher

Trample
Whenever another artifact enters, put a +1/+1 counter on Arcbound Crusher.
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Graaz, Unstoppable Juggernaut

Juggernauts you control attack each combat if able.
Juggernauts you control can't be blocked by Walls.
Other creatures you control have base power and toughness 5/3 and are Juggernauts in addition to their other creature types.

Ramroller

Ramroller attacks each combat if able.
Ramroller gets +2/+0 as long as you control another artifact.