The cost-reduction ability of Korvold, Gleeful Glutton doesn't change its mana cost or mana value, only the total cost you pay
It's not widely played anymore as other, better options have been used, but being able to target both creatures and planeswalkers helps to get rid of two potential problematic permanents, giving it versatility that other, similar cards don't have
At only two mana, you really can't ask for more
Additionally, in an elegant design choice, the cards that tap for two colors of mana have split costs on their front side and can be cast for only one color
Contents: 12 Magic: The GatheringAssassin's Creed Collector Boosters
In a Choco deck youll often be attacking with numerous small birds, and if some of them die to blockers or removal Soulcatchers' Aerie will massively buff the survivors