Death Unleashed: Invoker of the Dead

Humanity relies on Invokers to defend itself against Felbeasts. Colin Larkin is the only SSS-rank Necro Invoker, but he fails to realize that forming pacts with long-dead creatures is the key to boosting his power. After being betrayed and killed, he is reborn one day earlier. This time, he heads to a museum and forms a pact with the skeleton of a 160-million-year-old T-Rex.