My PCs recently derailed a whole bunch of my planning through creative play – which is fine, the surprises make the game more entertaining for me this way – they ended up in the Slumbering Ursine Dunes and here are converted monsters for my own reference with abbreviated 5e stat blocks.
Ghul flesh is wholly composed of a near-invisible translucent goo leaving only a dull pink skeleton to view. Because of this translucence in shadowy environs, they are invisible.
GHUL
AC 12, HP 16, Speed 30′
Saves +1, +0, +0
Challenge1/8 (25 XP)
Almost Invisible. Ghul’s have advantage on Stealth checks when in shadowy environments and are invisible if they remain motionless.
Bone Scimitar. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 1d6 slashing damage.