Well now ... here is the real purpose of Rock to Mud.
Super Mage! (c) : I activate my Prismatic Sword. I get 5 attacks per round. Prepare to die, elven wench!
Player of 9th level cute elven magistress: I cast my Rock to Mud, with you centered in it.
Super Mage! (c) : I step out.
DM: You can't. You're more than 10 feet from the edge, so you cannot step out. No saving throw is allowed, either. Can you fly?
Super Mage! (c) : I am a Wizard Jedi, with my Jedi Prismatic Sword. I don't need to fly!
DM: You keep sinking. You better do something quickly.
Super Mage! (c) : I use my Invinco Magic Resistance 250% to counter it.
DM: Mud is not magical. Magic resistance doesn't stop spells not aimed at you. You sink in over your head, and start to suffocate.
Super Mage! (c) : But wait. I'm Super Mage! (c) I can't be downed by a mere 5th level spell.
DM: Yes, you can be. Give me your character sheet.
Acererak, off-stage: Foolish, is he. Reckless, is he. Drowned, is he!
Ok, got a question.
Can you tell me more about Acererak?
What was he like, in life? (besides just being nasty and evil)
What did he do in life? (besides nasty and evil stuff)
If you could sit and have a conversation with Acererak, what would Acererak enjoy talking about? (besides endless magical research and evil stuff, obviously)
I mean, Acererak IS a legend. Many, many, many characters have died at his hands. Others (including Edena, my own PC) have survived. But most PCs of higher level have heard of the infamous demi-lich who resides somewhere in a Tomb, in a remote and desolate place out there in the wild blue yonder.
It would be pleasant to hear more about this famous NPC. Acererak, in all honesty, deserves a fleshing out. He's earned it!
'Go back to the tormentor or through the arch,
and the second great hall you'll discover.
Shun green if you can, but night's good color
is for those of great valor.
If shades of red stand for blood the wise
will not need sacrifice aught but a loop of
magical metal - you're well along your march.
Two pits along the wall will be found to lead
to a fortuitous fall, so check the wall.
These keys and those are most important of all,
and beware of trembling hands and what will maul.
If you find the false you find the true
and into the columned hall you'll come
and there the throne that's key and keyed.
The iron men of visage grim do more than
meet the viewers eye.
You've left and left and found my Tomb
and now your soul will die.'