#Glyph of Warding
Glyph of Warding
This assumes the Wizard is the big bad, or at least is on home turf.
Cast glyph of warding at 7th level, storing Tenser's transformation, with some trigger that the wizard alone can do, on your castle floor.
Wear plate armor and sit on your throne like the king you are.
When the invaders come in, stomp on the glyph and say "you're toast, interlopers".
This is very niche, as glyph of warding cannot move, but it's one of the options.