The Freeze Cluster Grenade is easily one of the best upgrades you can get in Batman: Arkham City. It improves your standard Freeze Grenade to freeze multiple enemies at once in a large explosion. This gives you breathing room, especially when you are fighting waves of enemies in a tight area.
Unlike your other gadget upgrades, the Freeze Cluster is a missable upgrade in the game. This is because it is tied to a side mission called Hot and Cold that you can choose to skip. Most new players will not be even aware of its existence until they are trying to complete the Freeze Cluster Grenade physical challenge. This requires you to freeze three enemies at once, which you cannot do with the standard Freeze Grenade.
You need the Freeze Cluster Upgrade for Predator Challenges. If you miss the upgrade, you will have to unlock it in New Game Plus for 100 percent completion.
You will automatically unlock and start Hot and Cold by advancing the main storyline of Batman: Arkham City. While tracking down Joker in the Steel Mill for the cure, you will find Harley Quinn bound and gagged. Free her and she will tell you about some stolen technology of Mr. Freeze that starts the side mission.
The stolen tech is basically the Freeze Cluster Grenade. We strongly advise you to complete Hot and Cold for the upgrade as early as possible. You are going to find a lot of use for it, especially in New Game Plus.
The stolen Freeze Cluster tech location in Batman: Arkham City
Mr. Freeze’s stolen technology (the Freeze Cluster Grenade) is located inside the Boiler Room of the Steel Mill. This is the same area where you fight Mr. Hammer, one of the Ambrovici Brothers, in one of the main story missions.
Head into the Steel Mill and make your way down until you come across the Freight Elevator. Use your Cryptographic Sequencer on the panel to open the elevator doors and then drop down the right elevator shaft.
Turn around and use a Remote Electrical Charge on the engine/motor to send the left elevator up. This will create an opening for you to jump down. Be quick about it because the elevator is going to come crashing back down.
There are several Riddles to solve in the Steel Mill as part of the Riddler Challenge.
Climb the higher ledge and go through the doors to enter the Boiler Room. You are going to find a lot of enemies here in the central room. Open the fight with Smoke Pellets and use silent takedowns to take out the enemies with guns first.
Once the room is clear, head to a small niche to the right of the Boiler Room to find the stolen technology of Mr. Freeze in Batman: Arkham City. Interact with it to collect the Freeze Cluster Grenade upgrade and complete the Hot and Cold mission.
You need the Freeze Cluster to unlock the Fully Loaded achievement in Batman: Arkham City.
How to get out of the Steel Mill
To get back to the Loading Bay and exit the Steel Mill, trace your steps back to the Freight Elevator. Use your Remote Electrical Charge at the bottom of the elevator to make it go up. Then quickly grapple the upper ledge to get back to the Loading Bay.
Do note that the elevator will not be empty. There will be three enemies stuck inside. Use this opportunity to test out your new Freeze Cluster upgrade. Throw a Freeze Cluster Grenade through the opening on the top of the elevator and drop in to beat them senseless.
How to use the Freeze Cluster Grenade in Batman: Arkham City
The first thing to note is that you will not automatically equip the Freeze Cluster Grenade after completing the Hot and Cold mission. This is an upgrade, not a new gadget, so you have to go to the WayneTech menu and upgrade your standard Freeze Grenade. It will be equipped in the top-left gadget slot.
Holding your throw button will highlight the trajectory of your grenade and its blast radius. This can take a bit of practice to use efficiently during fights.
If you are trying to complete the Predator Challenge or the Riddler Trophy, we recommend catching the attention of several enemies and then climbing up a lamp post. The enemies will then group up below you. Throw a Freeze Cluster Grenade at them and watch them get frozen to the ground in Batman: Arkham City.
Enemies that run over a frozen area will slip and fall down.