Sacrifice Essence

(You may cast a legendary instant only if you control a legendary creature or planeswalker.)

As an additional cost to cast this spell, pay 3 life any number of times.

Add a mana of any color for each life paid this way.

———{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}{line}
Blood is a decent substitute for mana.