A meaningful ritual system. 4E's ritual system broke down at high levels (well, mid levels, really) but 5E's feels like it was slapped on at the last minute. Every time I read a spell description with a casting time longer than 1 action and is not a ritual, I cringe.
An armor table that makes sense and isn't full of trap choices.
Warlords.
An armor table that makes sense and isn't full of trap choices.
Warlords.