Quoting Supergirl_peril:

My guess is they will hit her with this late in the episode. She will probably be taken back to the DEO, and of course Brainy will figure out what to do. I think the suit will only be short lived. Obviously it will protect her from the atmosphere, until again Brainy figures it out, but it can’t take long. Not even a full episode. They can’t keep Kara out of Catco too long. Kara obviously can’t be around until the atmosphere is safe for her.

That sounds highly plausible especially considering there are plenty of BTS shots of Melissa in the regular supersuit in later episodes. I think Kara will be stuck in a safe room at the DEO for most or all of E3 especially since that is supposed to be an origin episode for Ben Lockwood/Agent Liberty. By the beginning of E4 Brainy will have made the face covering suit, which allowed filming of Supergirl in action in Melissa’s absence. By the end of E4 or the first scene of E5 the atmosphere will be safe. My question is how did Mercy get Lex’s device. Lillian got hers from one of Lex’s vaults, which only Lena can open. Plus Lillian seemed surprised Lex finished that project implying he only had time to make one. Furthermore if the Graves siblings were working for Lillian at Cadmus I would think they would’ve given the device to her. Lena isn’t Supergirl’s biggest fan right now but that’s a far cry from wanting Supergirl dead or forced off Earth so I can’t see her helping Mercy willingly. I could even see the DEO/Alex asking for Lena’s help clearing the Kryptonite from the atmosphere and Lena agreeing to help. At the very least Lena wouldn’t a Luthor device associated with Supergirl’s death/exile.

Quoting Supergirl.tv Admin:

I think @Supergirl_peril is right, they are going to put kryptonite into the atmosphere. With Superman off world, they think it will get rid of Supergirl, but that is why we see her in the face covered Super suit later on. I bet Brainy will figure out a way to remove the kryptonite from the atmosphere later on.

You're probably right on, with that. It's a really efficient way to allow for those 1-2 episodes with minimal time commitment from Melissa, since they filmed most of episodes 3/4 while she was still on Broadway, then backtracked to episodes 1 and 2.

I'm pretty confident we'll be back to the normal suit by the end of episode 4, or sometime in episode 5.

Looks like it'll be good! SG on Sundays is a nice reward for the daily humdrum of a work week.

Looks like the device they used to pollute the air with lead to defeat the daximites. Now they are going to use a small does to put Fear into Supergirl . Big mistake. So far it looks like Mercy Graves has all the answers for dealing with Supergirl. As much as I like to see Supergirl put in peril, I will like seeing Supergirl kick Mercy's butt.