Do the 3 stack?
No but you might want to keep both.
For example: Superior Potency IV item...great for all spells up thru 4th level. 50% boost in "effectiveness"
Devotion VI Item: For spell leves I-IV the Potency would rule, but for 5 and 6th level healing spells the Devotion Item would come into play.
It is a lot easier to find Devotion VI items than it is to find Potency VI items, let alone SUper Pot items.
Sarlona - The Ko Brotherhood :Jareko-Elf Ranger12Rogue8+4E; Hennako-Human Cleric22; Rukio-Human Paladin18; Taellya-Halfling Rogue16; Zenako-Dwarf Fighter10Cleric1; Daniko-Drow Bard20; Kerriganko-Human Cleric18; Buket-WF Fighter6; Xenophilia-Human Wiz20; Zenakotwo-Dwarf Cleric16; Yadnomko-Halfling Ftr12; Gabiko-Human Bard15; lots more
Binding is Admitting Defeat ~ YndrofianPlook~Squidgie~Eyern~Irnbru~Grotesque
Of The O.S.D, Argonnessen
Myrrhl ~ Myrak ~ Myriarch ~ Dorkamyr ~ Myrauder
The New WDA-like-thing : DDO Damage Tool
The Path To Enlightenment: learning to heal in stages : Sneaking Tips : Raid Flagging Instructions