According to Felina's report, there were two Level-8 dragons and more than 200 Wild Beastmen. This opponent was a bit too much; the two Level-8 fighters were especially hard to deal with. This matter was kind of troublesome.
During the earlier fight, Nana and Todelron had tied. Felina had basically tied with the 300 Wild Beastmen. She could have killed them all without any help, but she would pay a big price too. Injuries were unavoidable, and she would consume a big portion of her dragon power too.
Now, not only had Todelron been revived, but he was stronger too. Plus, there was also Theron who was just as strong. Nana and Felina couldn't fight them off alone. Link had to join.
By doing so, he wouldn't be able to protect the Beastmen anymore. Considering this, Link said to Felina, "We can't wait passively for the enemy. We must attack first."
