Arachnostaff

Staff, uncommon (requires attunement by a spellcaster)
  The silk sacs on end of this staff are never still; they writhe with the thousands of spiders that inhabit them. Such staves are favoured by those who worship the spider goddess.
  Web Walker. While attuned to this staff you ignore movement restrictions caused by webbing.
  Swarm. While holding this staff, you can, as an action, cast the swarm cantrip at will.
  Mother’s Gift. You always have the spells conjure animals and web prepared. The first time you cast one of these spells after a long rest, it does not consume a spell slot if cast at its base level. If cast without expending a spell slot in this way, the conjured animal must be some kind of spider.
  Rare version: Add the spider climb spell to Mother’s Gift; the first two times you cast one of these spells after a long rest, it does not consume a spell slot. When you cast a spell granted by Mother’s Web, you gain a +1 bonus to the saving throw DC of that spell.
  Very rare version: Add the spider climb spell to Mother’s Gift; the first three times you cast one of these spells after a long rest, it does not consume a spell slot. When you cast a spell granted by Mother’s Web, you gain a +3 bonus to the saving throw DC of that spell.