Asteri, Cowl of Kruphix

Wondrous item, artifact (requires attunement):   Kruphix wears Asteri, a cowl made of Nyx. Kruphix uses this cowl to help govern the cycle of time. He counts few followers among the population so none have been known to receive this power. However, should he grant this item to a mortal it would be to aid all of Theros.   Cowl of Time. If you are a worshiper of Kruphix, you gain all the following benefits for which you have the required piety:   Piety 10+

• You have resistance to necrotic and radiant damage.
• You may use your reaction to reroll a saving throw. You must use the new roll.

  Piety 25+

• The Cowl grants a +1 bonus to spell attack rolls and to saving throws of your spells.
• The Cowl has 1 randomly determined minor beneficial property.

  Piety 50+

• The Cowl grants an additional +1 bonus to spell attack rolls and to saving throws of your spells.
• The Cowl has 1 randomly determined major beneficial property.

If you aren't a worshiper of Kruphix, the Cowl has 2 major detrimental properties, both randomly determined.   See "Artifacts" in chapter 7 of the Dungeon Master's Guide for details on randomly determined properties.   Spells. While wearing the cowl, you can use an action to expend 1 or more of its charges to cast one of the following spells (save DC 18) from it: hold person (2 charges), blink (3 charges), haste (3 charges), slow (3 charges), Legend Lore (6 charges), Scying (6 charges), time ravage (9 charges), time stop (9 charges).   Time to Act (Requires Level 12 or Piety 10+). The cowl has 4 charges and regains 1d4 expended charges daily at dawn.   Time to Learn (Requires Level Level 15 or Piety 25+). The cowl has 8 charges and regains 1d6+2 expended charges daily at dawn.   Time to Think (Requires Level 17 or Piety 50+). The cowl has 12 charges and regains 1d10+2 expended charges daily at dawn.   Destroying the Cowl. To destroy Asteri, its fabric must be disolved by the stongest acid known to man: the stomach acid of the Kraken Tromokratis. After a month in Tromokratis' belly, its energies are freed and return to Nyx.