You can use mag cells on the third evolution mags (Kama, Ila, Ribhava, Varaha, etc).
https://wiki.pioneer2.net/w/Mags#Cell_Mags
https://wiki.pioneer2.net/w/Mags#Third_evolution_Mags
I haven't liked many of the other recent changes, but this is by far the worst.
I was never really interested in playing the new Classic Mode, but I didn't mind adding a new way that people can choose to play if they want to. But removing an existing game mode that has been around for years...