Balancing with this should be done in comparison to Mummy, not Skeleton.
Worth noting that mummy is actually above the ATK/Cost efficieny curve when compared to skeleton (1 for 1 < 4 for 5). This card breaks even at 1 for 1 cost/ATK if an upgrade is counted as a free -1 cost.
So this is essentially Mummy and Abomination combined and
elementshifted. The resulting theme is somewhat bland and the resulting creature seems to tread on Wyrm's niche a bit.
I can't really say much about this card - it's very generic in both flavor and effect (Oh, so it's Mummy, except for Dragons.), and that heavily detracts from the card's appeal for me. Is there any way to fix that issue a bit?