For only two Red mana, this little Goblin Rogue allows you to cast Goblin spells from the top of your library
Torbran is sure to mourn his fallen ally for the rest of his days
If we compare it to Boneyard Wurm, we can get a better picture of how good it might be: 3 creatures in graveyardBoneyard Wurm (1G for a 3/3)Ghoultree (4G for a 10/10) 4 creatures in graveyardBoneyard Wurm (1G for a 4/4)Ghoultree (3G for a 10/10) 7 creatures in graveyardBoneyard Wurm (1G for a 7/7)Ghoultree (G for a 10/10) If we construct a shell in which we expect to be able to place a lot of creatures in the graveyard, then Ghoultree compares favorably to Boneyard Wurm
Even though the Roil tokens are only 2/2s, Omnath will still deal damage if they die, so making more is key
Then, when they come back, you get that cool triggered ability again
All those tapped Gates are going to hurt the mana base, but we really need the space, especially if there's going to be a functional shrine theme as well