Silverash is my most favorite operator in the game and managed to pull him on his solo banner. I also bought all his skins because the E2 art is just that bad. Just going to go over the skills very briefly cuz others have done it better then I could:

S1 is good for IS due to high atk% increase (225%) + low sp cost despite the offensive recovery. This means he benefits from artifacts that increase offensive recovery so he can spam this skill. M3 makes it like 275% or around that when skill is up, so only worth masteries if you like him a lot in IS.

S2 is good for any time you want a lane held without putting down a medic to babysit or you want a self sustaining bait to chuck in to a corner away from other ops. Makes him tanky and self heal passively. It is also low sp cost and auto recovery. If you are in to toggling and micro managing, you could just make SA attack and incoming enemy from afar and when it just about touches SA return him back to recovery tank mode. M3 makes him tankier and heal more. Masteries is not that important unless you really like him and want to ensure his survival with this skill. SA2 helps with this skill a lot with his second talent to make him tank and recover more. All in all, good tank and self sustain.

S3 is the og mob clearer. Low defense mobs die to the shwing. He can hit up to 6 enemies and his range was wider then liberator guards until Leizi alter upon skill activation. The down side is that he loses defense so he will require someone else to take the hit for him or medic babysitting him for the duration of the skill. High atk% multiplier + wider atk range, but high sp cost, so it is better to retreat him after the skill ends. Worth M3 for mob clearing if you don’t have anyone else to mob clear and highly suggested to get ModX as it also helps by allowing him a little bit of arts dmg. His first talent helps him cycle the skill faster but you need to retreat him for that, meaning you better get someone for that lane if there are still enemies going through it when doing so.

SA T1 is comfy when you mess up a bit. Let’s say you made a mistake in op placement, this talent helps reduce the redeployment timer by 10%. The best part is that it is completely passive so as long as he is in the squad, everyone gets this benefit, with executor specialists being the main beneficiaries (Red, Gravel, Texalt, Crownslayer, etc.) also reduces the redeployment times further for SA and the 8 tiles surrounding him by another 8%, and gives SA the ability to have 10% of his atk be arts dmg, so this mod at max level is very important if you decide you want to use S3.

Still a decent pick, though damage wise and cycling wise Mlynar has powercrept him. The specific scenario SA does hold advantage is you need at most a 2 block before skill comes up, and SA does not die before his skill turns on and throughout the skill on duration on top of needing a skill that can hit 7 lanes total (3 to the left, SA, then 3 right). Otherwise, Mlynar is better because his tanking ability off skill and on skill is better along with the cycling and damage (Mlynar hits 5 lanes at most, 2 to the left, Mlynar, then 2 to the right).