ABOUT MONSTERS

Name		  																				                Kill Weapon		   										       
Headless 	                        	         knife/guns				                               
Zombie	                                       knife/guns
Banshee		                      blue/orange/purple crystal(s)
Ghouls                                        knife/guns				                               
Ooz			                                                guns
Invisible Demon	                            guns
Nightmare		                                     guns
Electric Orb		                                   guns
Skitter			                                           guns
Sentinel		                                 green crystal
Flamethrower		                               guns
Ghast		                                        	    guns
Venomous Skitter                         guns
Greater Nightmare       	  guns (armour piercing)
Purple Monster	                         gas mask*
Green Ooz		                        none (get poisoned)

* Note:  It is generally believed that the gas mask does not help, though some have claimed that they were not damaged by the Purple Monster when they had it on.

POTIONS:

Clear Blue: healing
Bubbling Red: time slowing
Pale violet: temporary invulnerable/iron skin
Thick Brown: poison -> to get by the Green Ooz


CRYSTALS:
(Judicious usage of crystals is strongly recommended; i.e., don't use them unless it's absolutely necessary)

Yellow: Communication with dead soldiers
Blue: Freeze
Orange: Burn
Green: Earthquake (area damage)
Violet: Lightening (area damage)
Black: Turn to stone (not many uses)