That´s exactly where I am at. I was so ready to spend my few coins today, but not even the 3 ☆ costumes that are over in this thread here: 🧪 Early Information on Round 3 of Season 3 Hero Costumes [Part of The Beta Beat v53] are out yet 
Are there other events this month, where you have currency to summon?
I imagine there is a big bunch of players who believe that “just summon, it´s all rng anyway” and I tend to feel that way too. Just, it feels discouraging getting, say, Nordri, who I already have, without his costume, if his costume is live next month. I´m sorry, I´m not the best to advice you. I´m tempted to save my few coins now.