Haste Rule 702.10 Glossary

A keyword ability that lets a creature ignore the “summoning sickness” rule. See rule 702.10, “Haste,” and rule 302.6.
Prowess Rule 702.108 Glossary

A keyword ability that causes a creature to get +1/+1 whenever its controller casts a noncreature spell. See rule 702.108, “Prowess.”

Rulings (2)

July 26, 2024 Wizards of the Coast
The cost reduction applies only to generic mana in the total cost of instant and sorcery spells you cast.
July 26, 2024 Wizards of the Coast
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as a flashback cost), add any cost increases (such as kicker costs), then apply any cost reductions (such as that of this ability). The mana value of the spell is determined by only its mana cost, no matter what the total cost to cast that spell was.

Other Printings

The List (plst) Secrets of Strixhaven Commander (soc) €0.22 Bloomburrow (blb) €0.77