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Release the coolant by using Batman’s grapple or a partner’s gadget on a specific valve or pipe in the given area.
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Collect the spray bottle by having Gordon or another character interact with a foam‑related device once the coolant is free.
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Defeat the giant plant by repeatedly wetting its vines with the spray‑bottle gadget so Batman can safely attack the glowing weak points.
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The stage is built around switching characters and using their unique tools, so keep an eye out for green‑highlighted interact markers and canisters.
A fight‑scene‑style puzzle in LEGO Batman: Legacy of the Dark Knight has you release a coolant line, grab a spray bottle gadget, and then use that gadget to defeat a giant plant. Here is how to get through that section without getting stuck.
Release the Coolant details
How to release the coolant
When the objective is updated to ‘Release the coolant’, go to the boxes underneath it.

Punch and break them.

Break all of them.

Amidst the rubble, hit Build.

This will build the frame under the coolant.

Hit Detect.

Then go to the newly built frame under the coolant and select Insert.

With one character, move the button to the right.

With the other character, use grapple on the coolant.

And pull.

How to collect the spray bottle
Once you’ve release the coolant, you’ll get a spray bottle. Go towards it and collect it.

With the spray bottle collected, the next barrier to the giant plant will open.

How to defeat the giant plant
The giant plant stage is a multi‑phase arena fight where the plant slams its vines and seeds while Batman and his partner must work together to bring it down safely.
Use the spray bottle and use it to spray on the giant plant.

Do it a few times.

Once the plant gets weaker, hit it to destroy it.

Once you have released the coolant, grabbed the spray bottle, and taken down the giant plant, you will have cleared one of LEGO Batman: Legacy of the Dark Knight’s more hands‑on puzzle‑combat sections. This stretch sets up later uses of the spray gadget and reinforces the game’s focus on teamwork and environmental interaction, so treat it as a practice run for what comes next in the story.