The first part of the Wigwump battle takes place in the abyss. The Wigwump attacks the gang as they descend down using their Jet Packs. It attacks by breathing fire on them. Use the Jet Pack's ram attack to damage the Wigwump. Throughout the chase, the Wigwump will randomly pop out of the holes to attack. Halfway down, the Wigwump changes strategy and chases the gang. Just keep heading down while avoiding the rocks and staying ahead of the Wigwump. When you reach the end of the abyss, ram into the window on the right and let the Wigwump break the rocks. The gang will then drop to the Wigwump's burrow, thus starting the true fight.
This is the actual fight with the Wigwump. The boss attacks by breathing fire on parts of the ground, causing it to heat up and damage anyone on it. At lower health, it will circle around in its lava pool and heat up all three parts of the arena. Simply fire at the Wigwump until it retreates into its pool. But be ready to dodge as this is the precursor to the Wigwump breathing fire from one of the three holes in the wall. After enough damage, the Wigwump will cause a rockfall, summoning Deadgrubs and making a springboard appear. Hop on the springboard to activate your Jet Packs. Use the ram attack on the Wigwump until it falls to the ground stunned, then fire at it until it recovers. Repeat this strategy to defeat the Wigwump.