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That's awesome advice. Thanks for that. And yeah, all the research I've been doing has been more so with the renting of those summoners. Any advice on the CL summoners to level up?

I'm not an expert, so I'll just share my idea :)

Before you decide I think you should open your packs, then you should choose the best summoner who fits with your new cards.
I read a guide where an expert says that for a newbie are more important the monsters, and to rent the summoners to reach the silver league.

I think he considered the $/BCX: a rare monster is under 1 dollar, the cheapest summoner is over 3 dollars, if you like to own cards than renting them, I would tell you to buy monsters and rent summoners.
Personally, I don't like to rent, so probably that's what I will do...

Unless summoners become really cheap, in that case, I would probably go for the cheapest (probably the light summoner)

(sorry for the English, I'm Italian)