User blog comment:Willbachbakal/Singleplayer Plasmids/@comment-1330314-20100419075932

There's gonna be Scout 3, but level 4 would need too many new powers: at level 2, you need to come up with two entirely different new abilities for each plasmid and at levle 3 that number goes up to a total of six. If there was a level 4, the sum would go up to fourteen. Besides, level 4 plasmids would be a bit overkill.