AbdulAlhazred
Legend
You can definitely use weak foes at high level - but there should be dozens or hundreds,
not 12. My 5e group of 11th-14th level PCs just spent the last two sessions fighting
several hundred baseline skeletons; the Cleric's two Turn Undeads alone took out around 70.
Well, we killed 400 zombies a couple sessions ago. 95% of the damage was done by simply standing on the other side of an opening that they had to pass through and maintaining concentration on a Cloud of Daggers (IIRC I upleveled it a slot). It was tedious, as each zombie passed through the buzz saw we poked it with several attacks. 90% of them fell at the door, the other 10% required a little extra, but it wasn't exactly super hard. Still basically a wizard gig.