The Gate
An emerald interdimensional portal that has stayed open for decades without flickering, and the reason the Tower exists.
History
Emerald in hue, eerie in shape, exquisite in design. Establishing a gateway a quarter its size would demand an immense reservoir of mana, yet this one has never dissipated — not even a flicker to suggest its caster's strength has waned.
It is described as a parasitic scar upon reality that was never meant to exist. Who cast it, and why, remains unanswered.
Armies from both sides have crossed it countless times, each claiming the other struck first. Human scholars teach that the demonic hordes poured from the green abyss and set everything alight. That was never the truth.