Fight the Power Word, Kill

With the right magic you can go into a painting.
Inside everything is lifelike (to you) but stock-still – people and animals are living and warm to the touch but frozen in place. You can plunge your hand into a river but the water never flows.
Viewed from the outside, you're in the same style as the painting.

You can leave a painting:
a) the way you came in (this takes a few moments)
b) through another part of the same series or triptych (2d10 x 10 minutes, through strange dark passages)
c) through another painting by the same artist (1d6 hours, lowest 1 of 2d6 if it's via a portal visible in the painting)

If someone looks at a painting you are in, you're frozen for as long as they look at it. You don't perceive this but time passes in the outside world.
E.g. If you spend half an hour in a painting that someone looks at for 10 minutes, you experience 30 mins but actually emerge 40 mins later.

If someone spots you in the painting they could come in after you.
They might also fix you in place by getting a friend or servant to keep looking at your painting, making it easier to find you.