Heat Plasma Batteries are a rare resource in that you can farm to craft strong gear from various endgame item blueprints. Certain missions you unlock by progressing the story have enemies with high chances of dropping this material. With the changes made to Season 1 of the game, there are more opportunities to farm Plasma Batteries than ever before.
One of the main reasons to get a Heat Plasma Battery is to research an essential material for Ultimate Valby. This Ultimate character in can be unlocked for those looking to make strong endgame builds with weapons and gear they've collected. Other strong items like Executor Polymer Syncytium and Energy Activators can be made using this type of Battery.
The only places where you can get Heat Plasma Batteries are from enemy drops in specific missions tied to regions you unlock. As you progress through the story, you open up new areas to explore and tackle quests for different rewards. For this type of Plasma Battery, you are better off trying to challenge missions in these areas:
The listed missions in these areas can only be accessed when you unlock the Hagios region in. This section of your world map only opens up late in the campaign, after you finish the main story mission.
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The Acquisition Info for Heat Plasma Batteries describes how you can get them from completing the and missions in Hagios. However, this page also says how monsters defeated in these missions could also drop the item.
No matter what mission you choose to tackle, it is better to do quests in Hard Mode for increased item drops. Grinding has been reduced in Season 1 from the new 1.1.0 update for by making it easier to get rare drops from enemies. This includes the Heat Plasma Batteries, which typically only drop from Elite enemies, or tougher foes with yellow health bars you encounter during a mission.
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