Effects & keywords
Barrier: Blocks damage to the head/body, consuming stacks equal to the damage blocked.
How the math works
Barrier stack x (1 + 20%).
When it runs: Runs before every effect application is processed. It continues only when this unit is the target and the effect is in the Barrier category.
What it applies to: Any Barrier landing on this unit, from its own skills or from an ally (for example a Bubbling's death Barrier). Only AFFECTER_Barrier carries the Barrier category in this build.
Things the tooltip does not tell you
- It changes the stack before it is applied, so Guard Barrier, Mocking Grin and Fire Cloak Barriers are all raised.
Read out of the game binary of build 25846389. Refactor.Combat.SkillRelated.SKILL_Fortified.Passive_Fortified$$OnEnable@0x941224, Refactor.Combat.SkillRelated.SKILL_Fortified.Passive_Fortified$$AddFortifiedRoutine@0x9413E4
Numbers
| Range | 1 |
| Start delay | 0.2s |
| End delay | 0.2s |
| Cooldown | 0s |
| Energy cost | 0 |
| Skill points to learn | 5 |
| Required level | 0 |
| Basic attack skill | no |
| Delay scales with attack speed | yes |
| Can target over walls | no |
| Raw values | 20 |
Prerequisites
Unlocks: 
Mocking Grin
Tree position
Fortress Skill Tree - Tier 1, column 2