Every Torchlight: Infinite season includes new mechanics that change how you can play the game. Season 1 introduced the Dark Surge, a force corrupting monsters in maps, the pinnacle boss - Tidemaster Keegan and the Corrosion system. By reading this guide you're going to learn how to fight the Dark Surge and get rewarded with special loot like Familiar Nexus and Seed of Worry.
Encounter
Players start randomly encountering Dark Surge in Chapter 4.
Every zone that has Dark Surge displays a purple progress bar on your screen with some of the monsters marked with a purple icon on the minimap.
After killing some of the marked monsters, the bar fills up. Once it's full, press the button to summon additional monsters to kill. The more monsters you've killed through the map, the more waves you can summon. Magic and rare monsters give more progress.

Pro Tip: Summon Dark Surge monsters during other long encounters like trials or map bosses to save yourself some time!
Rewards
When you summon Dark Surge monsters an icon appears next to the progress bar that determines what type of rewards the current wave of monsters drops. Possible rewards are:
- Weapons
- Armor
- Trinkets (Belts, Amulets, Rings)
- Compasses
- Crafting Materials
- Memory Cards
- Hero Relics and Memories
The first summoned wave of Dark Surge monsters after the map boss has died has a chance to include a mini boss. Killing it has a chance to drop an Edict - special keys needed to face the Dark Surge pinnacle boss Tidemaster Keegan. They are very valuable so make sure to save up and use at least 1 wave after killing the map boss.

Keegan

To encounter Tidemaster Keegan you need to go to the Void Rift at the Netherrealm and place 3 Edicts - Edict: Dart, Edict: Dive, Edict: Ruin to start the fight.
You can also add 4th, much rarer Edict: Doom to summon "Uber" Tidemaster Keegan which is far harder but with improved rewards.
Corrosion
Corrosion is a special way of enhancing Legendary Gear that requires Corrosion materials - Aemberon Core or Familiar Nexus.
Aemberon Core is acquired by killing monsters summoned by Dark Surge in maps. Familiar Nexus is a Tidemaster Keegan specific drop and provides a new possible outcome when you are Corroding an item.


Here is a list of possible Corrosion outcomes:
- Mutation - Adds a random Aember base affix.
- Chaos - Randomizes values of the modifiers on the item.
- Arrogance - Upgrades 1 explicit modifier by 1-2 tiers.
- Void - Nothing happens.
- Desecration - Upgrades 2 explicit modifiers by 1-2 tiers. This outcome can only happen if you use Familiar Nexus to Corrode an item.
After Corroding an item it is put in Corroded state which prevents it from being Corroded again. When a T1 explicit modifier is being upgraded by 1 tier it turns into a new T0 Aember modifier which is usually extremely powerful.
WARNING: Crafted Gear cannot be Corroded!
Summary
- Killing monsters infected with Dark Surge fills a bar.
- Summon Dark Surge monsters and kill them to get extra rewards.
- Use at least 1 wave of Dark Surge after killing a map boss for a chance to summon another boss.
- Use Edicts to summon the pinnacle boss - Tidemaster Keegan.
- Use Aemberon Core and Familiar Nexus to Corrode your Legendary gear.
- Getting an Aember modifier on your item by Corroding it can completely change how you use it.
Credits
Written by Zen_M.
Reviewed by Xtra37, Raxxanterax.