[Uh-Nu-Buh]

Even at 25 gems it isn't worth it. Too easily killed off. Compared to other summons, it just isn't worth it. Take Behemoth for example (in death), or Wyvern even (if you move on to air). You could spam Wyvern and overwhelm an Eater easily.

25 Fire gems could Forge an Incinerate wand and a Fireball wand. Two of each if you have a Hammer of Forge Lord or Global Forge enchantment. 4 of each if you have both. Much better use of resources....