Boggs Rule Clarifications: Some cards, like a couple of Adam warlocks events (karmic blast) have as part of the cost a choice without…

Question

Some cards, like a couple of Adam warlocks events (karmic blast) have as part of the cost a choice without the word choose, like “discard up to 4 cards”. Do you decide/choose how many to discard before resolving or can you stop when you want to as you discard one at a time?

Answer