Capturing the Eidolon Gantulyst grants a 5.29% chance to get an Arcane Pulse, killing it will not yield this arcane.
This enhancement synergizes with Nekros' Despoil Augment, as it makes Desecrate use Nekros' health to cast instead of his energy. Coupled with the health orbs generated with Desecrate this allows Nekros to heal nearby allies as he replenishes his own health.
Having Arcane Pulse installed twice provides two independent chances for it to trigger. If these occur simultaneously, both will provide health, granting up to 225 health.
The extra health from Arcane Pulse is not considered as being from a health orb, and thus will not affect Equinox's passive or Equilibrium.