The S2_22 is a freezing boss that was added on 4 November 2020.
The S2_22 has a light blue triangle for a body. On the back of the body, there is a trapezoidal drone spawner.
The S2_22's body can freeze enemies that it rams. Its drone spawners spawn Crashers that inflict the same effect as a Chiller.
- This is the third boss that is a type of Guardian (the others are Guardian, PS3_33 and AT4_BW).
- S2_22 is one of the only bosses to have a different leaderboard and defeat message name. The defeat message refers to it as "Blue Guardian", while the leaderboard refers to it as "S2_22".
- The other such bosses are PS3_33 and Hexaswarmer.
- It is in the same group as the other polygon bosses.
- This boss used have some AI problems ; it used to always move towards east, and the bosses's name would show up above it. This got fixed at PATCH 11/20/2020 (1).