You entered on the twilight Forest, and you start walking to the fire swamp, and when you arrive, you saw a giant cracked-open cave, and you saw something sleeping inside

Hydra: When you approach it, you saw that the thing is big....way bigger than you thought, and it have 3 heads? Eventually, you realize it's the hydra, you try to leave, but one of the heads wake up, and spot you, and then, the rest of them wakes up. She stands up, and the three heads look at you, growling aggressively