User blog comment:GeneralOwnage55/What is your idea for a new plasmid?/@comment-1703246-20100131184155

If you include Gene Tonics, I'd think of something along the lines of Pain Booster, which gives a general damage boost to Melee attacks and offensive plasmids, the less the heal bar has, the more the boost increases.

As for Plasmids, i'd go for Fear Inducer - similar to enrage, but makes splicers run away in fear.