Light Regeneration is a light power used by Light Jak during Jak 3. He gains control over this power as a gift from the Precursor oracle at the Monk Temple at the end of the "Find oracle in Monk Temple" mission.
This light power replenishes Jak's health meter by pressing 
then 
. During this, time completely freezes and Jak elevates under a light eco beam and regenerates his health, either fully or until his light eco meter is depleted.