If the Garden Knight was a piece of cake for you then you'll very quickly meet your match as you come up across the Siege Engine. This is one of the three main bosses of the game needed to earn a key to unlock a portion of the prison keeping the Heir locked up. In this Tunic Siege Engine Boss Fight Guide, we'll talk about the Siege Engine's attacks, strategies, as well as its weak point.
The Siege Engine is fought in the Interior of the Eastern Vault after you make your way through the Forest Fortress. He's a very large enemy with an extremely long reach. Interestingly enough while he has reach, and plenty of ranged attacks that will consistently be applying pressure to you if you get up close to his body there's far less he can do.
The Siege Engine has a variety of attacks but as long as you stay right under him you'll be out of reach for pretty much all of them including the variety of ranged attacks. If you stay at a distance you'll be at the mercy of his long-range melee swipes, short Gatling gunfire, and giant lasers. The Gatling gun will rapidly follow you as you move around the arena, if you happen to be at a distance when this attack begins do your best to make your way to the nearest point of cover and wait for the attack to finish.
As the Siege Engine takes damage he will summon Faeries as additional enemies for you to face. The safest way to deal with these is to get towards them and kill them as soon as possible. You could try leaving them around to deflect their shots and do damage to them and others, but it's just a safer bet to remove them from what is already an extremely difficult battle.
The Siege Engine has two weak points, one on his face and the other is the core that he keeps under him. You can hit the core for additional damage, the biggest issue is managing to make it to the core before he backs away or turns around. To ease this process for yourself you can utilize your Magic Dagger to lock him into place, you need to make sure you hit his face with it though otherwise he won't get frozen correctly.
As always you can also use freezing the Siege Engine as a time to pause and drink a Magic Potion.
After defeating the Siege Engine you'll earn yourself the Red Gemstone, one of the three main keys you're searching for.