The idea of trapping an undead using the very mana that it had been forcefully bonded with was already tough. But Walker was talking about using the elemental mana of the entire elemental light plane to be able to trap this radiant skeleton.
It meant that he would be moving much denser light mana with a much higher purity to create a trap of dense and pure light mana which would not allow the radiant skeleton the ability to move until they either degraded in to bone dust, or they gained understanding of their self.
Using his mana, Walker immediately began to pull on the light mana. Onyx saw that walker was focusing immensely on this while the radiant skeletons were approaching. Since he was the one with the greatest light affinity, he had no reason to ignore what was happening. He moved to defend Walker.
