How long would someone survive, and what would he be capable of, if locked inside a metal cage and dropped into an ocean with heavy weights?
Here's the scenario. The big bad is known to dispose of naughty underlings using the aforementioned cage. To prevent easy escapes, the cage is kept in an anti-magic field that extends to just below the water's surface, and any obvious magic items will be confiscated. A small material component or focus could be hidden in a pocket, but would have to be retrieved before you drown. The mole is afraid of being found out, so he plans to escape; he knows some magic, and can prepare specific spells in readiness for the inevitable.
(Side question: What would actually kill him? Pressure? Inhalation of water?)
- How long is he alive and conscious? Obviously there'll be no casting hour-long spells. He cannot breathe underwater, though he can hold his breath.
- If the escape method (eg spell) depends on speech, how possible is it to speak underwater?
- Somatic components (gestures) - how long do you have before you're pinned down by the water?
Answers based on reality are preferred over those based on RPG rules, but if specific spells etc are needed, borrow from the definition of D&D 3.5th Ed or Pathfinder.