If target's SP is below 0, boost crit chance proportional to target's SP
After a successful evade, lower STagger Threshold by the evade skill's power at a (5x Gloom Res.)% chance
1 ally with the highest SP deals +10% damage to enemies with lower SP.
Jefe Sinclair is a weird Identity that trades offensive power in favor of boosting his defensive options. Not only his base defensive stats are really high, but he can also avoid being staggered early in the battle. Furthermore, his 1 and 2 skills have below-average power and you're unlikely to win any clashes with them, but thankfully his skill 3 is an outlier that also boosts his survivability.
And considering that his speed is most likely the lowest in the game among all Sinners, it is not that hard to make him the 'tank' of your team. Still, the issue is that in Limbus, you don't really need tanks and most battles are decided by which side has more offensive capabilities.
Also, it's worth noting that Jefe Sinclair has no support for his base EGO nor Impending Day EGO. His support passive is possibly the only thing why you would be bringing him at all.
decent support passive.
can take a beating.
but you don't really need a character that does it...