A cardholder's worst nightmare is having an entire attack ready to commence, only to have an opponent play a card that steals energy
Dredge was originally called reclaim and was basically a regrowth effect

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For three mana, that's not the greatest rate in the world, but there are plenty of targets in multiple formats, and finding ways to get more interaction into your decks is always good
It's really hard to do t1 Champion of the Parish into t2 Ash Zealot