According to the "close enough for who it's for" effigy drop rate calculator on the wiki and elsewhere, K'ril should drop an effigy every ~37 kills. K'ril also counts as a greater demon, so I figured I'd give him a shot for effigy collecting by getting greaters as a slayer task. I took a level 125ish (On purpose, I wanted to make sure I got 90% of the drops) to zammy GWD and we got 40 K'ril kills in an hour and 10 minutes, and he only recieved one boss drop, leaving 39 kills for myself at a chance at an effigy. Of course the agreement was that I split the drops with him after the trip was over. Point being: If you want effigies, take a relatively low level with you and duo Zamorak on a populated world for ~1 effigy per hour assuming you have nearly maxed gear. Using a partner allows you to split up the damage from the minions and hold spare supplies. If the partner is using a combat familiar they can also use it to pull the minions post-kill. Good plan? Bad plan?