Heroes of the Frontier: The Summoner

From publisher blurb:

Everybody had an imaginary friend while growing up. It turns out that the Summoner's ones were more real than most. His latent psionic skills allowed him to contact the spirit world and befriend the entities living there. With time and practice, the Summoner became able to help those friends cross over to our world. In a place like Prometheus where everyone and everything is out to get you, the ability to call upon true friends is worth more than a metric ton of iridium. Especially when those true friends come equipped with sharp claws and deadly fangs.