Draconic Polymorph

Chose a target if not willing must make a wisdom saving throw (can fail if wanted) The target must succeed on a Wisdom saving throw or shape-shift into Dragon form for the duration. That form can be any dragon you choose that has a Challenge Rating equal to or less than the target’s (or the target’s level if it doesn’t have a Challenge Rating plus 10). The target’s game statistics are replaced by the stat block of the chosen Dragon, but the target retains its alignment, personality, creature type, Hit Points, and Hit Point Dice. 

The target gains a number of Temporary Hit Points equal to the Hit Points of the Dragon form. The spell ends early on the target if it has no Temporary Hit Points left.

The target can't cast your spells while in dragon form

The target’s gear melds into the new form. The creature can’t use or otherwise benefit from any of that equipment.