Grave Situation by Louisa Masters Special Edition

Are you looking for...
...a snarky mage who’s forced to go on a quest to save the world with his twin sister (the dragon rider), and that one really hot healer who saved his life when he did something phenomenally stupid? Oh, and he's at war with his horse. She's winning.

Meet Talon Silverbright. He's in a Grave Situation.

He’s not the hero they deserve, but he’s the hero they’ve got.
No, seriously. Talon wants to know what he did to deserve this. What would make a sentient rock decide that he of all people should be the one to save the world from zombies? That’s right. Zombies. Because apparently a higher power decided that teaching magic to teenagers wasn’t enough of a challenge.
With a ridiculously attractive healer (who may or may not hate him), his sister (who he miiiight have a forbidden telepathic link with), a sentient god-like rock (that can only communicate via yes/no vibes), a disdainful dragon, and a rude matchmaking horse by his side, he just might be able to save the world.
Or die trying.