Mirror Image. Which wizard is which?
Add in a Dimension Door, and then, when they do figure it out, you move to another section of the map and take your remaining images with you, thus muddying the waters again. Mirror image says you can rearrange at will while moving, so even add in expeditious retreat, or for added punch, haste.
Toss in a blur or a displacement, which would, at least in my opinion, apply equally to the illusionary you's, and wow - would it ever be hard to grapple you.
Plus, they are all low-ish level, so you won't waste your big damaging spell slots on them.