blizzard64 
Ok, I understand that in the case of Cozy Glow, when she got the power of Discord she was in control because she was already evil and that's why Discord's magic didn't corrupt her, but Cozy Glow was very logical and manipulative, due to that she could not control the magic of Discord.
And in the case of Pinkie Pie, because obviously she was very illogical and "Out of context", so she could control Discord's power very well, unfortunately that didn't protect her mind from corruption ... The same thing happened to Pinkie Pie in comic # 57, just like Sci-Twi (Twilight Sparkle) and Gloriosa Daisy from Equestria Girls.
And in the case of Pinkie Pie, because obviously she was very illogical and "Out of context", so she could control Discord's power very well, unfortunately that didn't protect her mind from corruption ... The same thing happened to Pinkie Pie in comic # 57, just like Sci-Twi (Twilight Sparkle) and Gloriosa Daisy from Equestria Girls.