Altar of Shadows

At the beginning of each upkeep, each player exiles the top card of their library. The player who exiled the card with the greatest mana value takes an extra turn after this one. If two or more players' cards are tied for greatest, the tied players repeat this process until the tie is broken.

1G, T: Counter target activated ability from an artifact source. (Mana abilities can't be targeted.)

T: Add R.

Whenever a player casts a creature spell, that player adds G.

1R: This creature gets +2/+0 until end of turn.

Whenever this artifact or another artifact enters, put a charge counter on this artifact. 3, T, Remove a charge counter from this artifact: Draw a card.

Whenever you cast an artifact spell, draw a card.

Equipped creature gets +2/+0. Equip 1