Sludge

Sludge is a boss in Golden Sun: Dark Dawn. It is a lizard-like monster that haunts the Phantasmal Bog and, by extension, Kolima Village. It has a resistance to Mercury attacks and a weakness to Jupiter.

Some of its known techniques include:
 * Crush (target: single character)
 * Tail Slap (target: 3 characters)
 * Call Skull (summons a member of the Skull monster line)
 * Healing (heals up to 300 HP)

Defeating it will reward players with varying amounts of experience points and coins, dependant on how many Skulls were defeated. Also, Matthew can acquire the Crush Tusk after returning to Kolima.

Skull monster line
The Curse Skull, Haunt Skull, and Shield Skull are monsters that support Sludge in battle and are not encountered anywhere else in Dark Dawn. Like Sludge, they are all weak to Jupiter-based attacks. Sludge begins its battle with both a Shield Skull and a Haunt Skull. Even if players destroy the skulls, Sludge can simply summon more with its Call Skull monster skill, although only three skulls can acompany Sludge at any one time.