Yet more infinite Mana

: Add .

Whenever Karn blocks or becomes blocked, it gets -4/+4 until end of turn. : Target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value until end of turn.

This artifact doesn't untap during your untap step. : Add . : Untap this artifact.

: Untap target artifact creature.

This artifact doesn't untap during your untap step. : Add . : Untap this artifact.

: Add .

This artifact doesn't untap during your untap step. At the beginning of your upkeep, you may pay . If you do, untap this artifact. At the beginning of your draw step, if this artifact is tapped, it deals 1 damage to you. : Add .

: Add three mana of any one color.

Activated abilities of creatures you control cost less to activate. This effect can't reduce the mana in that cost to less than one mana.