I made a room full of boulders and I want my guy to try to get through it without getting hit. The problem is I cant figure out how to cause the damage to my guy when he gets hit.

use the event command - change hp - decrease hp ?
if you want hp damage appear visually like number of hp appeared, then use a script or some sort , i know a few but not sure if its allowed to post here or not.

ps. the boulder moved magicaly?

You should set the event to Collision trigger and set it as supercow said.
Otherwise, you could trigger it in parallel process, set phasing mode on and set it as below:

#comment: calculate X difference
>Variable[1] = This event X
>Variable[1] -= Player X
#comment: calculate Y difference
>Variable[2] = This event Y
>Variable[2] -= Player Y
#comment: setting branches
>Conditional Branch: Variable[1] == 0
>>Conditional Branch: Variable[2] == 0
#comment: deal damage (this is an example)
>>>Change HP - Entire party: -50
>>End
>End

If you set every boulder as above, it should work. I've used something similar many times...
You can use the very same two variables for every boulder.
I know it seems strange, but I enure you it works

Jens

Jens