Flinx Fur Coat

Summoners spend the opening hours of a run with nothing built for them. This is the exception, and it is worth a deliberate snow biome trip to farm the fur before you fight anything.

An extra minion is a large jump when your total is one or two, and the summon damage on top of it applies to whatever staff you managed to scrape together. The minion carries the damage while you spend the fight dodging, which is how the class wants to be played from the start. You will keep wearing the coat well past the point where its defense stops mattering, because the slot is the thing you are actually paying for.