Literally the best build if you dont need fire rate (i dont), dont like bane mods (i dont) and can't afford a riven good enough (i can't).
This can red crit if you take the time to aim the head.

[Ambush Optics] is a personnal preference, i always use 2.5x zoom, this mod allow to use the 50% crit damage bonus, and give you a lower zoom, way easier to use than the 5.0x

Arcane momentum is almost mandatory, it only cost about 20p and provide 150% reload speed on critical hit (and you always crit with the [Rubico]).

[Galvanized Aptitude] is great, but the [Rubico] cant really use status, and you want the 1hit ko, so a mod requiering multiple hits is just meh.

This is not for eidolons, i use it for everyday content because snipers feel so good and require some skills to perform unlike meta weapons.