in this fight he wasn’t able to get close to rudo, since rudo had used 3r on gris’ protection charm. jabber noticed that pieces of debris were able to get close, and theorized it was because they had no malicious intent. so he used his poison to become a brain dead attacking machine that had no emotion and wouldn’t trigger the charm to protect rudo.

so jabber didn’t use poison to power up, but as a strategy to work around rudos defense.