Although it has only one HP, its high evasion makes it hard to hit, its high Defense and Magic Defense can reduce the damage of many weaker weapons and spells to 0, and its attacks can easily kill a party member. When hit by magic, five copies of it will appear.
Skull Eater can easily be killed with the Ninja's Throw ability, Ranger's Aim ability, or the Geomancer's Gaia ability. The Will o' Wisp ability can confuse it and it will kill itself, but this method can fail if Skull Eater uses a normal attack instead of Incisor on itself. Stalactite can also kill them swiftly. One can also defeat a Skull Eater using Control and then have it use Special technique on itself. Their high evasion rate can be bypassed with Aim or Rapid Fire, but an axe, hammer, or a weapon with over 90 attack power is needed to get past their Defense. Later in the game, the Excalipoor can also be used as it never misses and always does 1 damage, and most higher level damaging spells, such as Titan, Bio, Firaga and Aeroga, are powerful enough to get past the Skull Eater's formidable Magic Defense. 1000 Needles is also effective since it deals fixed damage, bypassing Magic Defense.
Skull Eater is easier to kill after the worlds have merged, as the party will probably have weapons powerful enough to get past its Defense, as well as commands capable of bypassing evasion and spells powerful enough to get past its Resistance. It is useful for AP farming, particularly in Bartz's World, since it can be killed fairly easily using the Throw or Gaia commands and gives a high amount (between 5 and 10, depending on the amount of enemies) of AP. The monster also tends to run away while the battle is at an early stage, leaving the party with a 5 AP reward at no cost to the party. The Black Magic attack Bio also works well.