If 6th+ level spells are making high level play tricky for you as a DM, replace a 6th level slot with a 5th and 1st, 7th with 5th and 2nd, 8th with 5th and 3rd, and a 9th with a 5th and 4th. Same net power, lower power ceiling.

— Mike Mearls (@mikemearls) December 19, 2018