The Codex Terragnosis

Wondrous Item Legendary (this item requires attunement)

The Barrier Between Worlds

While this book resides in the Mundane World, sending a native of this plane to another plane, unwillingly, requires a saving throw.

Steward of the Earth

Once per day, as an action, you can summon an elemental of your choice to do your bidding. After 1 hour, the elemental returns to its home plane.

Stone and Sea, Obey Me

Once per day, as an action, you can cast cataclysm. Cataclysm (Warfare Magic) Target: 4 units, Attack: +12, Power: +15. Enemy units damaged by this attack must make a DC 15 Morale save or decrement their casualty dice twice.

Defender of Erenel

Once, a druid attuned to the Codex Terragnosis may wild shape and assume the form of the Phoenix (CR20). This form lasts until sunrise or sunset, whichever comes first, at which point the Phoenix dies in a flash of brilliant light. The druid must make a DC22 Constitution Saving Throw to survive the conflagration. The Codex Terragnosis itself survives regardless of whether the druid lives, and relocates itself somewhere safe on the current plane it resides.