You can move half your speed - see crawl.
As noted above, this is allowed under the crawl mechanic. However, keep in mind that crawling provokes OAs. This would significantly increase the power of the prone condition.Errata or not, I'm inclined to let you spend a move action to move (not shift) one square while prone, so you can try to roll out of the way of a monster's attack or the like.
This leads to situations in which it is convenient to have someone in your square. I'm thinking about letting characters shift in any case... thoughts?
Yet, as we where discussing, this limitation of movement is negated by the presence of an ally or an enemy in the target square.Consuming the target's move action to get up, therefor limiting possible movement.
Yet, as we where discussing, this limitation of movement is negated by the presence of an ally or an enemy in the target square.
Yes, I understand the rule and why it is there... as I already wrote several times, I have a slight problem with it. On the other hand, the situation is uncommon, so it's not a big deal.It's a rule that helps adjudicate where you are when someone is in your square.
One alternative, could be to deny a prone character the chance to stand up when an enemy is occupying his square. It make the condition more dangerous, but it doesn't happen very often.This would make Prone more powerful in the fairly unusual circumstance of standing up in an occupied square, as you would provoke OAs, but make it weaker if there are no adjacent enemies when you stand up, as you can get in a square of movement at the same time.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.