Sage | Sage

[OdinVanguard]

OT got his post in before i did, so ill edit that part out.

and an adjustment that could be made to mitigate SoP would be to have the shielding be based on damage done each turn, rather than flat attack power.

I'm still a little worried about the stacking, but if you make reduction based on damage done rather than just attack power, it should mitigate abuse with SoP. I think this will be pretty well balanced then.
Balancing concerns aside I think the concept is pretty darn sweet.

[rickerd]

4 dammage reduced is a bit much

[OdinVanguard]

4 is a bit high, but they are quite fragile and very expensive... Consider comparison to hope shield though, if these have to do damage rather than just exist, this opens up a huge range of other CC options. Freeze, stun, AM, and interesting even sundial (you get 1 round to put damage through for each). Also, your own shield could help as well: Dim shield and wings stop them cold. Fire shield and thorn shield and skull shield kill them off. Ice shield freezes them. Turtle shield stuns them. Fog and Dusk mantle will stop any that miss their attack.

In short, if they must deal damage to provide a shield effect, they are MUCH more easily countered. Every element will have at least 1 card to deal with them. The SoP combo will be much less effective, and a decent shield can prevent the Quint combo from paying off, or at least make it more difficult and costly. I think this warrants the high 4 pt damage reduction.

[Annele]

There's also the Sage -> Mitosis -> SoR combo.

[OdinVanguard]

There's also the Sage -> Mitosis -> SoR combo.

That would be quite nasty, to be sure, but again the creature is so fragile that this could go very badly.
Are you willing to invest 8 , 5 , 3 and 3 cards for a combo that can be countered by any number of single card retorts? Reverse time, lightning storm, plague, unstable gas, fire shield, otyugh ... you get the idea. I'm fairly certain that every element has a 1 card answer for much lower cost.

From a metagame perspective, the card and its combos are powerful enough to demand an answer, but said answers are so prevalent that they should either already be in most decks or else can be easily added without forcing major changes in deck construction.

[esran]

not every deck should be required to use CC. this card means all decks are required to use CC.

[OldTrees]

not every deck should be required to use CC. this card means all decks are required to use CC.

or evasion (Psion, Unstable Gas, Drain Life, Poison, _, _, Fire Bolt, Charger, _, _, _, Ice Bolt)

Edit: Though I agree that lower DR is called for.