Athgar the Armorer

Athgar can only be untapped in your untap phase. You may equip any artifacts to this card where the cost of equipping is the converted mana cost of the artifact. Artifact abilities stack on Athgar(e.g. if you equip several mana rocks, you may use all of them at once.)
Athgar the Armorer gets +2/+2 for every 3 artifacts equipped to it.