Hand of Gul'dan cannot be used in Metamorphosis, yet the counterpart is learned at 76.
Soulfire is learned at level 12, Molten core and Decimation are 69 and 73.
Why are these, they make no sense. Even less makes sense that Metamorphosis says that you can't use hand of gul'dan or corruption, but you can use corruption. Why not Hand of Gul'dan?