Fire 2 and Blizzard 2 need some actual design work, but I think consolidating Enochian/Fire4/Blizzard4 and Leylines/BtL are no-brainers. I wouldn’t mind a combined Despair/Umbral Soul button, either.

People who prefer separate buttons could just put the “same” skill in two different places, or Square could make it possible to still assign single skills from the action screen.