If you already have Frog, Doge and Snek go for rune. But if you don't have all three of them, might want to consider get them via summon shop. These 3 can be fit in most team at current meta.
Even if you already have that summon there are still chances you gonna get a dupe so it's 1/11 chance to get it from pull while collecting it.
You can lower the risk by only start to buy summon frag after you pull a gold from summon treasure to reset the counter.