ingredients:
a clear water brush
a mottled texxture with lots of empty little spaces (b1 old lava texture with the yellow parts removed.)
lighting source from the floors like those found in the museum
some steam fx (particles floating upward.)
A alt fire flare entity.
place the mottled texture on the clear water brush.
use lit floors (orange lighting is best) for the floor and sides of the "pit"
flag alt fire entity to go of right above player who's fallen in. Allow to burn full damage time even if player gets out of "water".
Run water brush on its slowest setting and add steam effect for flavor.
sluuurp...
Now that's good lava!