If you have been through the Horror of OSRS GP the Deep quest you've also gained access Dagannoth cave. It is possible to place a cannon there and begin destroying Dagannoths by using a Rune Crossbow as well as Broad Bolts. Bring prayer Potions or Potions for Ranging Potions top equipment you can put on and runes to aid in Bones to peaches spell. Given that these monsters are ranged and...