EVENT INCURDAMAGE
EVENT_INCURDAMAGE is a constantly running event that checks for any damage inflicted into the player, and if the player is wearing any armor[SHIELD], any damage received will have (20+RAND[30])% of the damage dealt to the armor and the rest dealt to the player's health until the armor runs out.
If "setvar RETURN -1" is placed in this event, armor will not work in the normal manner, and it will allow you to maker your own formula for armor.