Cold-Bloodedness to spam abilities and Blizzard. Focuses on crit and cooldown to defeat enemies quickly. Glass cannon build so be mindful of surroundings. Two pieces of Annihilation set allows Blizzard to go beyond 6sec duration to allow for an extra hit of damage.

Reactor Sub Stats to looks for:
Chill Power Boost Ratio
Critical Hit Damage
Critical Hit Rate
Tech Skill Power Boost Ratio (keep in mind this will only boost Blizzard damage and not Frost Shards or Cold Snap)
Skill Cost can be useful but will lose out on overall damage.

Component sub stats to look for:
Auxiliary Power: Max HP / MP Recovery Out of Combat
Sensor: Max MP / MP Recovery in Combat
Memory: DEF / MP Recovery Modifier (Use Firearm Proficiency Modifier if using for weapon leveling)
Processor: Honestly free choice. Item acquisition is always nice. Max Shield and Toxin Resistance can help survival but already a glass cannon build so it wouldn't be a whole lot.

Overall this Viessa build is very useful for Reactor Bosses and Infiltration Operations.