The PureStreamV person in chat is referencing KyoStinV Very well known in the Arknights community for making video guides on how to get through stages and events, especially time limited ones like Contingency Contracts. He also makes guides on getting through stages with low(er) tier operators. Melantha is very often used, so "Activate Melata Skill" is something you will hear quite often.
Say isn't Mashiro Don Quijote? The hat is the same with the little missing part, spear, shining knight armour and on the horse back. Do we have a tag for it? The only ones about him are the fate and project moon ones.