Wonder Twin Powers... Activate!

Just watched "Gopher Moat" Wonder Twins vid @ Beyond the Black Gate blog... and that was weird... Got me thinking about ol' Zan and Jayna, and their "magic" rings.  Lots of potential here for a cool magic item for D&D...
So the PCs find a pair of rings, obviously a matching set, maybe with settings which appear to interlock (why else would anyone think to touch them together?...).  Wearing one on each hand and touching them together doesn't do much, or maybe causes some sparks or something (save vs Stun &/or minor electric damage), but if TWO PCs each wear one, and touch them together ("Wonder twin powers activate" command phrase optional, but fun!)... hmmmm....
- Each PC can transform as per the original W.Twins; one can assume the form of Water (wave, puddle, ice, steam?), the other can assume animal form (possibly incl "monsters", dinos, etc)
- Expanded options: maybe one is the "Elemental" ring, and wearer can transform into Fire, Earth, or Air... the other is the "Creature" ring, allowing Polymorph into any "natural" creature, or maybe just humanoids, reptiles, etc.
- Limitations/Parameters:  both PCs MUST transform (not just one or the other - this could lead to interesting scenarios), Dispel on either affects both, Limited duration of course (random, predetermined, or even a "set" duration, meaning one MUST remain transformed for the duration, cannot change back until it expires...), both must be conscious & mentally sound to activate/use
- Maybe specifics are randomly determined when found...

Elemental Ring (d4)                                             
1. Air (whirlwind, Gaseous Form)                      
2. Earth (boulder, Wall of Stone, statue)            
3. Water (pool, Wall Ice, maybe even snow...)     
4. Fire (req. fuel source?)                                      

Polymorph Ring (d4)
1. Natural Animal (no fantastic monsters)
2. Humanoid (PC race, Giant Class...)
3. "Monster" (specific type(s), any)
4. Plant, Slime, Dinosaur, Mammal, etc

This could be the kind of "thinking player's" item I love to introduce... maybe having the Thief become gaseous to enter a locked room is perfect, but having the Wizard assume the form of a Hamster at the same time is less than ideal... or wow, what we need is the Fighter to be a Pegasus, so I guess the Cleric will have to be an Ice Cube for a few turns... yeah, gonna do this!