Cleric in my game wants to disadvantage the targets of his spells

@JustinTime4DnD @ChrisPerkinsDnDAn LG cleric in my game wants to disadvantage the targets of his spells on their save attempts. Suggestions? that's very powerful – would allow it in return for a use of channel divinity

— (((Mike Mearls))) (@mikemearls) August 12, 2016