Activating the Cold Mode changes a few things in Eighteen's gameplay.
-Upon activation, you're getting served a nifty circular gauge; the Infinity Engine Core! This now serves as both her Cold Meter and Power Meter.
-Power Charge is disabled. No power is gained from hitting the enemy or performing moves.
-Cold Bar fills automatically from time to time, indicating the current MAX threshold.
-It'll temporarily stop filling up if you're guarding, getting hit or performing any Special Moves.
-Each EX or Super move will consume no power bar, but instead drain from the Cold bar.
-If the Cold bar reaches 0, Eighteen will enter "Overheat" Mode (turning the Infinity Engine Core red).
-In Overheat mode, you can still perform EX/Super moves but at the risk of breaking her Energy Core, ending the Cold Mode and leaving Eighteen in a dizzied state.
-In Overheat mode, the maximum threshold is lost.
-Eighteen gains access to the Accel Dance (detailed below).
-Overdrive Deadly Breaker can be performed from LV1 and upwards and cancels the Cold Mode.
-Unlike other characters, the mode will end at the end of the round even on win but she might get some power back depending on her left-over Cold bar.
-Depending on how far the Cold Bar is filled, Eighteen will perform a Finisher at the end of the Overdrive Deadly Breaker:
LV1 - Death By Degrees.
LV2 - Infinity Engine.
LV3 - Demonic Twin Dance.

Did you like SF Alpha 3's V-ism? Well then you're in luck, because this is kinda like it!
-Increased speed thanks to her infinite energy core. Her moves will play out 200% faster.
-Basics can be chained without limitation.
-Afterimages will also hit the enemy.
-Performing a Throw, an EX move or a Hyper will end the mode.
-Getting hit or blocking an attack will also end the mode.
-You can't use her LV3 Super anymore; only her LV1 and LV2 Supers.
-The duration of the Accel Dance depends on the Cold bar MAX threshold (not the current Cold charge).