In my opinion:
- midrange: nope. you donāt consume enough cards to need the refill (heck, you may overdraw), also while this kind of decks donāt go for tempo as hard, they usually need to curve out, and semi-skipping a turn (if you canāt play at least 6+ mana worth of stuff on the same turn as Skull) is usually not optimal. I expect the card to be too clunky here.
- control: probably not. Control decks tend to hoard cards. For one it means that Skull is often not cast with Outcast, making it a pretty bad card. It also means you may overdraw. It gets you closer to fatigue. Best use case would be fishing for an answer, but in that scenario you prefer cheap draw so that you can play said answer on the same turn.
- combo: absolutely yes. Draw is important in those decks, and hitting a combo piece with the discount is absolutely massive.

