Talk:Mag (Warframe)/@comment-81.230.89.198-20130412220532/@comment-89.0.102.43-20130413013141

I think that´s the part he was referring to:

Scratch (Warframe Abilities) - Commonly dropped by Infested

Your best bet would be to grind infested defense missions and hope for the best. Or you re-craft your Mag Warframe to get all 4 of her ability mods.