The Book of the Blade — Eric R. Asher

A forbidden magic. A hidden world. Two mages journey to a realm not meant for mortals.The magic needed to save Damian requires three coins. One of which is from a world not their own. Thankfully, Cornelius, an elder blood mage, knows the way.After passing through a Seal between worlds, Beth and Cornelius realize traversing the strange new realm will require the help of a Sage. But all is not well in the Shadowed Lands. Eldritch influence is seeping in, diminishing their powers, and threatening the realm's very existence.To learn more of the coin, Beth and Cornelius must stand with the Sage, but the price of knowledge may be their souls.