HP: 50
ATK: 43
DEF: 28
MAG: 43
MND: 20
SPD: This stat is an exception to the rule. The higher value from level, level bonuses and equipment, the higher the boost.
I'm checking the Boost Skill thing now...
Having the Boost Skill increases the bonus you get from Viole. Not just for speed, but for every stat.
So, I would presume that you need to pour level bonuses in SPD and use the Speed Boost skill to make Cirno fast in some capacity(this is in light of a post on the previous LoT2 thread, where someone displayed that they could make
Patchouli relatively quick, so Cirno is not hopeless in the speed department here).
Also, if damage against enemies is a necessity, then one would think that Diamond Blizzard is the only skill that Cirno has that isn't composite, so it shouldn't have too much of an issue in doing damage if one focuses on the ATT Stat via Voile Boosting. And if all else fails, the Monk skill set, along with a maxed out Leaning Iron Mountain(closest thing to a nuke that the subclasses have, attack wise), plus said point setup should make it so that the Ice Fairy can actually hurt people.
Her debuff, however... That requires some thinking. Is the SPD debuff a large amount when it actually takes effect? Because if not, then I was right about Cirno being seriously nerfed, meaning that she'll need the Hexer Subclass skill set to remedy that. If it is, though, then either the RNG hates you or it might be bugged to an extent, and there's nothing that you can do about it, sadly.