Bamboo RFs all have similar skills that involve gaining charges after the Skill is ready and needing to aim to spend all charges, dealing increasing Damage based on said charges.

This entire RF type has a few significant issues:

Bamboo RFs are generally not recommended, as simply using a standard self-buffer will yield usually better results. M99 is no exception.

M99 has a very high Damage stat of 157 but a pitiful ROF of 32. While certainly not the lowest in her class, or even her rarity, it does significantly affect her damage capabilities -- a fact that becomes all the more egregious when considering her Skill. M99’s Skill, Steady Shot, has her take aim for 2 seconds, then shoot the furthest target from her for 8x her normal Damage. This Skill has an insane potential for burst damage, but it also has an absurdly long Initial Cooldown of 15 seconds and a standard Cooldown of 16 seconds means that it will hardly ever see use. There are only a few boss battles in the game that will last long enough for M99 to activate her Skill once, let alone twice, meaning that in most situations she might as well not have a Skill at all. When combined with her low ROF, this makes her one of the slowest mob clearers out of all RFs -- a distinction one definitely should not wish to possess. M99’s tile buff, like other RFs, isn’t particularly notable, reducing the cooldown of one HG by 18%. This is fairly standard among 5 star RFs; though they may have some variation on the tile position, the buff is always the same. In conclusion, M99 is not a particularly good RF. Inside her niche, she’ll demolish a high HP enemy in one quick burst after a long period of time waiting for her Skill to come off cooldown, but her uses are limited outside of these specific situations. Outside her niche, she slows down the mob clear of any RF team, making her terrible for general use. If one truly desires good boss burst, IWS or a charged shot RF with a shorter cooldown, such as Mosin and Springfield should be used instead.