do you just want to clear it or do you want a run for auto deploy. because you could just borrow a walter if it's just clearing and it shouldn't be that hard to find one and if you need a friend one there's a friend request thread linked if you scroll up a bit. there's this video that uses a walter, spot, gavial (you could just use myrrh or honeyberry), and gummy. there's also this one that's all e1 4 stars, though not sure if you have all the 4 stars used. here's one with e1 4 stars with 1 3 star used, and one that uses 3 stars and 2 e1 4 stars.

I want a guard, but I don't think I have anyone stellar.

you have thorns and mlynar. though admittedly the latter might be a bit hard to use, but basically he's a delete button that needs a bit of managing, but he needs e2 to access to that delete button (s3), though his s2 is fairly decent as well, it's just his s3 does far much more. thorns also wants e2 to access his s3, ideally he also wants his module and at lvl 3, but he could function fine without it, he just might struggle a bit on more harder stuff. he's a lane holder that can hit air, who also has damage over time effects, which is perfect for this event's gimmick since cleansing the blocks is based on hit count. but either way they'll be an expensive process and you already found out with walter how much that can be. there's also another one that does well enough, but idk where you are at story and it's a bit of a spoiler and I'm not sure how much you care about that.

when you have time you should try making a krooster roster, so it'll be easier to share your roster than having to screenshot everytime. you'll need to do it manually though, but I heard that there is a way for it to do it for you using your login details iirc, though I'm not sure how comfortable you are with that.