@Andro7: I don't think it's worth to run him against creature decks just for instant speed boardwipe and the occasional kicked "Blink of an Eye". I'm pretty sure you will need the slots for other things. There is not enough room for 8 Teferis.
If u ask me this is good in almost every matchup. Against control ez win. Creature decks instant speed board wipes op op. Combo when they cant react to ur counter ez. Just overall op
Good for control mirrors and against Reclamation Decks. Not so good in other cases although you can sort of cycle him.
Only rare should lead to cheaper prices.