I kind of like it, I just think its a little underpowered. It gives too little back for the cost.
Have it generate 2 shards of mark's element then. That makes it worth the card space to include metamorphosis.
For instance, think of the shard of void combo. With this you can get 18 shards of void... thats actually probably quite potent.
Also, consider Shard of Integrity combo, being able to flush out the ratio of integrity shards to other shards could be very useful in tuning the stats and abilities of the golem you get.
Speaking of shard golems... How would this interact?