Overview
Our adorable little medic GSh-18 sadly doesn’t improve a whole lot with her upgrade. While there is an interesting idea at play, it is ultimately not that practical.
Her new Skill 2, Twin Star Protection, gives her a chance per shot to grant all allies on her tiles with a 1-HP shield. This chance is equal to her Crit Rate and can be stacked indefinitely. Also, her Crit Damage during Skill 1 is increased and she receives all the usual upgrades like better stats, improved tiles, improved Skill 1, etc.
The concept of infinitely stacking shields is an interesting one, but it sadly falls flat once you account for two major flaws. One, the chance being equal to her critical rate means these shields proc unreliably. Two, the shields just don’t have enough HP to be useful compared to other sources of HP Shields like MPL.
While you could theoretically have GSh-18 proc her shields on each attack and improve the tank’s survivability quite a bit, it is ultimately too small of a shield and too unreliable in its activation chance. Her upgrade is not downright awful, but it is not worthwhile for most commanders.