[Spirrow]

I just collect grenades and drop down to the screen with the lever,
jump over the chasm and walk to the edge of the screen but not
into the area with the two sligs. Then I crouch there and chuck
a grenade into the next screen, wait two or three seconds before
rolling into the area so that I can see the one of the sligs blow up.
then I roll back into the previous screen to avoid getting shot
by the second slig. You have to time it perfectly, but make
sure you are far enough away from the grenade to avoid
being killed yourself. The grenades won't kill the slig if you
not on the screen and see it blow.

Then when you are on the previous screen, you have to wait until the sound of the last slig walking is the farthest before running into the screen and climbing on the platform before it can shoot you. Possess and destroy that slig.

It took me forever to beat that level.