I find phase shield affects maybe one out of every 50 games I play against mono aether, and it usually only ends up helping me as I steal it. Plus, if your the one running the card, you'll probably want 6, which would cost 30
and 6 draws, whereas other shields cost one draw and just about 5 quanta. That one shield will probably be enough if the opponent doesnt have a shield. Phase shield just makes it overkill when it works. (not common) I dont usually mind much when the opponent plays phase shield, but I mind if he plays any other, except other and gravity.