Is a Rakshasa immune to the damage of the new Dragon’s Breath spell?

Does the “Path to the Grave” feature only apply vulnerability, but keep immunity and resistance intact?

Catnap spell: are elves unable to be affected by it, even willingly?

If a Storm Sorcerer casts Dragon’s Breath lightning damage, does that initial casting trigger the extra damage from “Heart of the Storm”?

Does an Improved Pact Weapon Ranged Weapon generate it’s own ammunition?