Kaalrati Broken

Kaalrati Broken is the second boss encountered in the Crypt.

Even with its face shattered and its substrate leaking, it was still relentless.

Its battlefield is 5x3, with the first and last rows on your side filled with natural obstacles.

Observed stats:
On Chosen difficulty, its power is - ''When Kaalrati takes damage from the enemy: FLINT-SPAWN (4/4) enters battle. Once per turn. 1 use.'' It always cycles through the same FLINT-SPAWN variant:

On Burdened or Doomed difficulty, its starting power is - ''When Kaalrati takes damage from the enemy: FLINT-SPAWN (4/4) enters battle. Once per turn. 1 use.'' It spawns the following FLINT-SPAWN variant, which starts a cycle of stronger versions of the spawning effect and FLINT-SPAWNS:

Strategy
It is typically recommended to establish a strong board presence before attacking Kaalrati Broken, to avoid starting the FLINT-SPAWN cycle before you are ready to deal with it. Once he’s out, ignoring him and focusing on Kaalrati Broken can be a valid strategy if you can sustain the onslaught of rusters long enough to finish him.

Due to Shielded, very few cards can disable this boss’s mechanic. One possibility is to get to steal FLINT-SPAWN and then use it on your own side, provided that there is no other enemy on the board or that you are lucky enough for it to be picked. However, on difficulties other than Chosen, will restart the cycle by giving Kaalrati Broken  again.

A more reliable alternative would be to use to apply Blackout if positioning allows, thus preventing Kaalrati Broken from regaining his status effect. From then, you can either debuff FLINT-SPAWN or leave it be since other units are likely to pose more of a threat. Note that even if you don’t target it, FLINT-SPAWN will likely die sooner or later by attacking your units, so this strategy only gives you temporary reprieve on difficulties other than Chosen.