i do agree that quintessence does change things a lot and does seem to favor rainbow decks. If that Phasing were to take over for immaterial idk how many people would like that. From what i have seen and others have stated that the shields that have a % like fog shield and the
shield is that even if its 50% it still seems higher (90%). So even if phasing were implemented i think it still would seem like they are exactly the same with a small chance that they would get hit by something.
I believe there are some card ideas / forum threads about making cards that remove immaterial status. either that or we need more things that affect immaterial so its not a huge "gamebreaker"
Also, there are more shields that affect immaterial.. Fog,
shield, Thorn Carapace, fire shield, diamond shield still reduces damage, turtle shield does bubble them, ice shield does freeze them. It isnt like they dont have any way of dying.