The fight continued...
Augustus is blind and has burned a lot of spells, his goal is still to rescue Della.
The Witch needs to either kill her foes or get away.
The two mages each know that the other is covered with magical defenses; immunity and anti magic shell would be obvious contenders. Augustus isn't as good a mage as the witch, but he does have Della, the Dwarf, who can get out soon and level the playing field.
The Witch headed to the door, opened it, pointed inwards and yelled "KILL".
Augustus didn't know what he was facing, but he had to do
something. Enclosed space, had to hope that he could kill whatever it was with an area of effect without dying himself, but he was blind... Pulled out a wand of fireballs and let rip.
Didn't hurt anyone very much (6d6, save for half) except for the witches pet displacer beast; it failed its safe, took full damage, and died.
Della continued digging.
Next round, Augustus goes first. He has
fly permanenced, and reasoned that his safest place would be up by the ceiling. Anti-magiced, immunity... yeah, get out of melee range and wait for Della. Flew up.
The witch saw that the dwarf wouldn't be long. Now, even with his defensive spells up, on his own Augustus is a sitting duck. Yeah, anti magic shell is a pain in the ass, but there are ways of beating him to death; summon in some giants and have them pummel him to death with rocks, that would do. But she just doesn't have time, and she hasn't got memorised today any more spells to keep the dwarf in. Besides, she needs to alert the other Witches.
So, she casts another timestop, followed by two create magical monsters spells (summoning blast spores, which I treat as half hit dice, meaning that she fills the room and corridor with blast spores), casts haste, drops a delayed blast fireball, and then simply runs off.
The dwarf yells "AHH! BEHOLDERS".
Augustus is still blind, being buffeted by scaley things... They clearly aren't beholders, and they're clearly summoned. He casts
dispel magic, falls painfully to the floor, dispelling about half of the blast spores but failing to deal with the delayed blast fireball (which he doesn't even know about for sure).
Next round, he casts a forcefield around himself, in a cone. I rolled some dice, did a sum, and it transpired that he had been lucky and not trapped any blast spores with him, but he HAD trapped the delayed blast fireball... Well, he just about survived that as it went off at the end of the round. Next round, as he's licking his wounds, the dwarf tossed her egg of wonder out under her forcefield, covered the gap with a towel, and let the giant snake that had appeared bite one of the blast spores... esplosions rocketed up and down the corridor outside as they set each other off
So, round one over. It'll be interesting what happens when the party manages to catch up with the three witches. Bear in mind that the witches are trapped; they can't leave, they can't cast teleport, dimension door or similar to get out.