The level caps for monsters are the same in wild and modern format. So a level 4 rare summoner is the best you can use.

In silver league Kelya frendul is king. The new Riftwatchers summoners at the moment don’t come close.

Combine him with diemon shark, heal, supply runner for the swiftness and watch your opponent melt because they can’t hit him. And when they finally kill him, make sure that djinn oshannus is behind him.

Also at the deeplurker as nothing beats that 3 damage opportunity attack