Great Desert Prospector

When this creature enters, create a tapped Powerstone token for each other creature you control. (They're artifacts with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Sarinth Greatwurm

Trample
Whenever a land enters, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Stone Retrieval Unit

When this creature enters, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Argothian Opportunist

The Mana Rig

Whenever you cast a multicolored spell, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")
{X}{X}{X}, {T}: Look at the top X cards of your library. Put up to two of them into your hand and the rest on the bottom of your library in a random order.

Thran Spider

Reach
When this creature enters, you and target opponent each create a tapped Powerstone token.
{7}: Look at the top four cards of your library. You may reveal an artifact card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Koilos Roc

Flash
Flying
When this creature enters, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Arbalest Engineers

When this creature enters, choose one —
• This creature deals 1 damage to any target.
• Put a +1/+1 counter on target creature. It gains trample and haste until end of turn.
• Create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Junkyard Genius

When this creature enters, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")
{1}{B}{R}, Sacrifice another creature or artifact: Until end of turn, other creatures you control get +1/+0 and gain menace and haste.