Syntax is one of the most recurring Bosses in Freedom Planet, being fought in 3 Stages, taking on different forms in each fight.
Syntax is both the Mid-Boss and End-Boss of Thermal Base, taking on 2 different forms.
For the Mid-Boss Fight, Syntax will transform into a spider-like robot and attack the Player in a room with Lava walls and spike floors on both sides. The Player can avoid damage from her attacks with a Fire or Metal Shield. Once defeated, Syntax will retreat, then at the sound of an alarm, a torrent of lava will flow into the area, and the Player has to outrun it.
- Lava Cannon: Syntax will absorb lava from one side of the room and fire it at the Player to inflict Stunlock on them. This attack can be angled, determining whether the Player should jump or crouch.
- Spike Shot: After her armor is damaged, Syntax will move onto a rail and grabs spikes from the floor and shoots them at the Player.
For the End-Boss Fight, Syntax will transform into a squid-like robot to attack the Player in a large room with platforms, slopes and lava. Her lava attacks can heat up the metal platforms, which can hurt the Player if they stand on it long enough. Once defeated, Syntax will explode in a poof, ending the Stage.
- Lava Cannon: An attack shared with her Spider-Mode, Syntax will suck up lava and fire it at the Player, this time in either a full burst or in a rapid fire.
- Spike Balls: Once she's taken 1/3's damage, Syntax will descend into the lava, where she launches a set of 3 large Spike Balls in the order of left, right then center. She will use this attack twice in this fight.
- Circular Saw: Once she's taken another 1/3's damage and used the Spike Balls again, Syntax will emerge from the lava in the form of a large, Circular Saw that will move across all the edges of the room before descending back into the lava.
At the end of the Schmup Stage, Syntax will transform into a crab-like robot to attack the Holodragon or Shang Mu Tanks. Unlike her other forms, this form has a Health Meter that measures how much damage she has taken. Once it's depleted, Syntax will explode, allowing the Player to proceed to the next Stage: Battle Glacier.
- Laser Blast: Syntax will fire 4 massive laser blasts from her pincers, tracing the Player's position before firing.
- Laser Shots: Syntax will spray fire multiple shots from her pincers in multiple directions.
In Final Dreadnought 1, Syntax will transform into her strongest form, which can take on multiple forms. She'll pursue the Player down an seemingly endless hallway with a laser beam in tow. Once defeated, Syntax will be hit and disintegrated by the laser, ending the Stage.
If playing as Milla, it is recommended not to use her Reflection Shield in this Boss Fight, as she'll stop dead in her tracks and risks getting hit by the laser.
- Tank-Morph: Syntax will transform into a Tank and fires a pair of lasers vertically, moving along the ground or ceiling.
- Train-Morph: Syntax will transform into a Train and absorbs energy from the laser and fires 3 energy beams at the Player.
- Pogo-Morph: Once at 1/4's damage, Syntax will start transforming into a Pogo Stick, jumping around in all directions, creating shockwaves on the ground as she bounces.
- Buzzsaw-Morph: Once at 1/2 damage, Syntax will start transforming into a Buzzsaw and moves along all corners of the screen.
- Plasma-Morph: Once at 3/4's damage, Syntax will transform into her Final Morpher Form and launches Plasma Spheres at the Player while clinging to the ground and ceiling. These spheres can be deflected by Milla's Phantom Cubes.