Arcbound Worker

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.)

Shrapnel Blast

As an additional cost to cast this spell, sacrifice an artifact.
Shrapnel Blast deals 5 damage to any target.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is this creature's power.

Arid Mesa

{T}, Pay 1 life, Sacrifice this land: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Walking Ballista

This creature enters with X +1/+1 counters on it.
{4}: Put a +1/+1 counter on this creature.
Remove a +1/+1 counter from this creature: It deals 1 damage to any target.

Arcbound Shikari

First strike
When this creature enters, put a +1/+1 counter on each other artifact creature you control.
Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Arcbound Reclaimer

Remove a +1/+1 counter from this creature: Put target artifact card from your graveyard on top of your library.
Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Throne of Geth

{T}, Sacrifice an artifact: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Plains

Sacred Foundry

({T}: Add {R} or {W}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Arcbound Mouser

Lifelink
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.)

Arena of Glory

This land enters tapped unless you control a Mountain.
{T}: Add {R}.
{R}, {T}, Exert this land: Add {R}{R}. If that mana is spent on a creature spell, it gains haste until end of turn. (An exerted permanent won't untap during your next untap step.)

Arcbound Ravager

Sacrifice an artifact: Put a +1/+1 counter on this creature.
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.)

Zabaz, the Glimmerwasp

Modular 1
If a modular triggered ability would put one or more +1/+1 counters on a creature you control, that many plus one +1/+1 counters are put on it instead.
{R}: Destroy target artifact you control.
{W}: Zabaz gains flying until end of turn.