Abstruse, Murkwood Capital

As Abstruse, Murkwood Capital, enters the battlefield, you may pay 3 life. If you don't,
it enters the battlefield tapped.
{t}: Add one mana of any colour. If this
mana is used to cast a nonhuman creature
spell, you may pay 2 life. If you do, untap
this land. This ability triggers only once
each turn.