I agree, Shard of Wisdom is overpowered (as I said in another topic) and in my opinion.
It's hard to counter it, spell-reflective shields are not only highly situational, but, they can be countered by the most boring way: by simply not playing the Shard. Even if the shield shows up after the first Shard was used, by playing un-Sharded creatures the damage balance can be easily reversed. (Eg. 1 unupgraded Phase Dragon + Shard of Wisdom = 14 damage; 2 Dragons -> 16 damage, minus 4 in case of Jade Shield = 12 damage. 3 Dragons ->24-6=18 damage.)
As I mentioned elsewhere, it boosts mono-Ether deck, which is already powerful withouth the Shard itself. (And, let be frank: a mono-Ether deck is not the peakpoint of deck-building inspiration...)
Even worse, if the Shard is paired with a Quintessenced creature. I met a deck with a Quint'ed and Shard'ed Forest Spirit in it...
Basicly, the "dream creature" is the one which ignores shileds and immortal at the same time, since in pratice, it can't be hurt. A Shard'ed creature is almost the same, and the card even gives ADDITIONAL damage. I think it's silly.
So, either the damage increase should be removed, or the immortality of the creature, as others suggested (if the name is misleading, re-name the Shard itself like, "Shard of Magick" or something like that).
Alternatively, a new idea: magick damage actually
is a skill and costs some quanta to use it. Like,
or so.