Summoner's pact

Among all magical classes there exist one that is considered the weakest and that is Summoner. Young Flake was member of adventuring team Lotus for quite some time, but now after confrontation of Death knight he is expelled. Now it's time for Flake to go on his own adventure and uncover mysteries of his unique summoing crest.
After surviving hell with Lotus, he joins up with his childhood friend Mika and they together explore dungeons and go on adventurers.
But what is this? A unique skill? What is that?