Staff of the Fossil Maker

Staff, very rare (requires attunement by a sorcerer, warlock, or wizard)

This cobbled-together staff of fossilized dinosaur bones carries with it a portion of the apocalyptic force that created them, as well as the power to survive them. When you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you instead take no damage if you succeed on the saving throw, and only half damage if you fail.

The staff has 10 charges for the following effects. If a creature is slain by a spell or effect created by the staff, its remains become petrified after 10 days have passed.

Spells. While holding the staff, you can use an action to expend 5 of its charges to cast either the firestorm or flesh to stone spell from it, using your spell save DC. Alternatively, you can use a bonus action to expend 1 of its charges to cast the false life spell from it as a 2nd-level spell.

Summon Tyrannosaur. While holding the staff, you can use an action to expend 4 of its charges to summon a skeletal tyrannosaurus rex in an unoccupied space that you can see within 60 feet of you. The summoned creature takes its turns immediately after you and follows your mental commands. It uses the statistics of a tyrannosaurus rex, has vulnerability to bludgeoning damage and immunity to poison damage and the poisoned condition, has darkvision out to a range of 60 feet, and is an undead instead of a beast. Whenever the tyrannosaurus rex takes 25 or more damage from a single source, it crumbles into an inanimate pile of bones. You can reform the pile of bones into the skeletal dinosaur by expending 2 of the staff's charges as a bonus action. The creature and its pile of bones share the same amount of hit points: if either the creature or the bones fall to 0 hit points, it turns to ash and disappears. Otherwise, the summoned creature and its bones disappear after 1 minute, if it crumbles to bones while the staff has 0 charges, or if you use this property again to summon another tyrannosaurus rex.

The staff regains 1d6 + 4 expended charges daily at dawn. When you expend the last charge from the staff, roll a d20. On a 1, the staff breaks apart into a heap of shattered bones and recreates the effects of the firestorm spell. The pillars of flame created by the storm in this way are randomly placed, except for the first one which is centered on your location.

"Our line is blessed twice over: first by the great cataclysm, whose fire still lives in our bones, and then by the Grymclover itself, whose shadows sheltered our scorched ancestors. Our spark of magic comes not from mere wit, but by our hunger for survival and the darkness we call home.

"Most of our ilk live to become tyrants in their own right; claiming the fearful tributes of locals makes the days longer and sweeter. But when that grows old, the retribution they bring always delivers a glorious death.

"So we remain, as our long-ancestors did when so many of their cold-blooded brethren failed. When we die, our very bones sing of our spark, and return it to the world. It is in our nature to endure in life and death, after all.

"And when those who slay us take those bones as trophies, our memory only spreads all the farther."

—Words of Grym-Mage Wrackjaw of the spellcarved throne, later slain by and become companion to the necromancer Caleidae