Ahi dice que hace daño que ignora la defensa no que se salte a la torera las reducciones como por ejemplo el assum, la unica reduccion que se salta es la proporcionada por la defensa que la ignora.
http://irowiki.org/wiki/Gravitation_Field
Amplify the gravity in an area around a targeted spot that will decrease the ASPD of enemies within range, as well as continually inflict irreducible damage (neither reduction gears nor defense have any effect on the amount of damage dealt by each wave). Although this skill can damage Boss monsters, it does not affect their ASPD. Gravitational Field inflicts a set amount of damage to WoE Emperiums that is determined by the skill's level. When used on Plants, this skill only inflicts 1 Damage, regardless of its level. While Gravitational Field is active, the caster cannot move or use normal attacks. The caster can however, use supportive skills like Quagmire, Safety Wall, Heal etc., for the duration of the skill.