If the children were lucky, he was asleep when they ventured through his cave, as the rhyme goes "Old Speartip is one deep sleeper, wake him up and you'll sleep deeper."
In The Witcher 3, Geralt and Lambert have to pass through Speartip's cave in order to reach the Circle of Elements to enrich a phalactery with elemental power. The player can either sneak through or use aard and blast through debris, and risk waking Speartip. Should the player decide to confront the cyclops, Lambert will spit on its corpse afterwards saying "That's for Voltehre."
Combat with Speartip is no different than combat with any other cyclops, make use of Quen to absorb unavoidable hits, and the use of igni's alternate form helps to damage him through a constant burning effect.