My idea is to add dagannoth kings. Rex should drop beserker ring (i), Supreme archers ring (i) and Prime seers ring (i).
Make the rings best in slot. Ring of stone gives currently +3 strength and +3 attack bonus in mage, range and melee. I would love to see if, for excample, the beserking ring (i) gives +4 attack and strength bonus in melee and +0 in mage and range. the same applies to archers ring and seers ring, this woudn't make ring of stone useless since the droprate of the new rings will be high and the rings will be expensive.
in order to gain access for the dagannoth kings it would be cool if you need to complete a quest with some hard requirements.
What do you think?
btw i am sorry if this has already been suggested