Wizard Spire of Arcanum AA, uniquely among class Spires, includes a level limit on the boost it provides: 48965 Spire of Arcanum XII WIZ/254 0s 0s 90s n/a Self 1: Decrease Spell Mana Cost by 30% 2: Increase Chance to Critical Nuke by 16% 3: Increase Critical Nuke Damage by 160% of Base Damage 4: Limit Type: Detrimental 5: Limit Min Level: 75 6: Limit Max Level: 115 (lose 5% per level) Increases the chance that your direct damage spells will land critically by 16%, the damage dealt by your critical direct damage spells by 160%, and reduces the mana cost of your level 75 to 115 detrimental spells by 30%. This makes its function decline on the new Terror of Luclin spells I think Wizards would probably find the requirement to buy a new rank to restore functionality copacetic, if the older rank can't be altered to raise the level cap.
At least it has been labeled "confirmed" and not "not a bug". I assume we will get a fix sooner or later.