Hidden Threat

"Hidden Threat" is a regular event that opens every several months. Its most recent appearance is May 27 to June 11, 2021. During the event, you can fight in a special campaign. The goal of the event is to unlock areas on the campaign map and win battles in those areas to earn currency that can be spent in the campaign store. This event is the exclusive place to buy Possessed Grant, as well as some event-themed premium units and skins.

The June 2020 release of the event added many new features, including a heroic mode and new equipment and equipment modifiers in the event shop. For full details, see the official announcement.

Campaign
The campaign contains 10 areas in the shape of a talon increasing in difficulty from top to bottom. The first area, at the top, can be unlocked for free. The rest of the areas must be unlocked by using an event resource: Violated eagle of the Empire (earned from PvP victories) or gold. You can unlock areas in any order. Once you win a fight in an area, that area will go on cooldown for a length of time. The resources required to unlock an area, as well as that area's cooldown timer, increase as you move deeper into the campaign map. To win a battle, you must either capture the enemy spawn point or destroy all enemy units. If your hero dies or the enemy captures your spawn point, you lose. There's no limit to the number of times you can lose in normal mode battles. The table below has a summary of the battles in the campaign map. Maps fall in two categories: most maps have torn shoulder straps as a possible drop, and require only fuel to run. Three maps have a chance to drop essence of madness, and these require torn shoulder straps in addition to fuel in order to run. All other maps only require fuel to run. Torn shoulder straps and essence of madness are not guaranteed drops and when they do drop you can only get one at most. All levels also always drop a Grant's Chest upon victory (however, if you get the Torn Shoulder Strap in "Relevant information", then this takes the place of the chest). Each level allows a standard size loadout of 1 hero and 15 other units; see below for full loadout details.

Event resources
There are six different resources that can be obtained during the course of the event.

Violated eagle of the Empire is a reward for winning in PvP while Hidden Threat is active. It is used to unlock areas on the map. Areas can also be unlocked with 5 gold instead per each. Violated token is a reward for winning battles on the campaign map. They are used to purchase items from the event shop. Torn Shoulder Strap is a reward for winning battles in 7 of the 10 areas on the campaign map. It is used as an additional cost to to start battles that may reward. In general, areas can reward either or, but not both. The drop chance is not guaranteed, so the player may receive either zero or one for winning a battle. Essence of madness is a reward for winning battles in 3 of the 10 areas on the campaign map. It is used only to purchase Possessed Grant (the event exclusive hero) from the event shop. In general, areas can reward either or, but not both. The drop chance is not guaranteed, so the player may receive either zero or one for winning a battle. Areas that may reward require  and one or more  to start the battle. Grant's Chest is a "reward" event chest for winning battles in each area of the campaign map. Unlike most event chests, Grant's Chests work like normal chests and go to the back of the queue. The occult trophy was introduced in the June 2020 update as a reward for completing Heroic Mode missions. It can be used as an alternate currency in the shop.

Event enemy units
The main enemies you will face in the event are corrupted versions of your own troops: Insane one (corrupted infantry), Head hunters (corrupted stormtroopers), Defilers (corrupted crusaders), Flayers (corrupted rangers), and Hammers of the Void (corrupted Hammers). Generally these function like stronger versions of their original troops, except for the Flayers, which become powerful melee units instead. Early missions (the first five) also feature other occult troops, such as lycanthropes, berserks, possessed, and bloody adepts in addition to the corrupted troops. The enemy also uses standard supports: artillery bombardments, mustard gas, and discharges. In the last level, Possessed Grant himself will appear to lead his troops, and will use carbonite bombs and lairs in addition to the regular supports.

Note that you can buy versions of the corrupted troops in the event shop. These versions are significantly more powerful than the base-level enemy troops that you will face.

Heroic mode
Heroic mode was introduced in the June 2020 update, and provides an extra-difficult challenge for those who have a strong lineup of heroes. You will need several good, strongly upgraded heroes for you to have a chance. It operates similarly to the heroic mode in the Christmas event Blood on the Snow, in that you don't bring regular troops. Rather, you have a lineup of 5 heroes, who can be supported with 10 supports. The supports cannot be landings or similar. The heroes can be released one at a time from a special panel on the right.

Before you can start heroic mode, you must unlock it at the cost of 50 violated eagles (as with other unlocks in the event, you can pay 5 gold  for each eagle  you are missing). You must fight the heroic mode battles one by one, with each victory unlocking the next battle. You have 90 minutes from when you start the heroic mode to complete it, and you start with 3 attempts, of which you lose one each time you fail a mission. You can recover lost attempts for 50 gold each. If you run out of time or lose all of your attempts, the heroic run ends and you must wait 16h for it to become available again.

The heroic mode missions award occult trophies, which can be used to buy advanced items in the shop or exchanged for violated tokens. In addition, completing heroic mode awards an additional 25 occult trophies for each attempt remaining. Completing a full run of heroic mode with all attempts remaining rewards 175 (100 from battle rewards and 75 for attempts remaining).

A note on the AI's strategy: on most maps, the AI can target their Lair and Summoning very close to your spawn point, generally around the nearest capture point.

The full data for the Heroic mode missions is as follows:

Event shop
Note: the June 2020 update added the first set of items with an occult trophy cost, as well as occult trophies as an alternate cost for Possessed Grant. The December 2020 update added the last five supports, the last four hero skins (as well as reducing the cost for other skins), the Gauss research points, the kinetic protection and Kevlar Armor Plates, and the repair kits.

End of event rewards
Starting with the March 2020 edition of Hidden Threat, rewards were given at the end of the event based on accumulated rating. Reaching a new tier qualified players for the rewards in that tier. The rewards are not cumulative.

Detailed map information
The tables below give more detailed information on each map, including the description, troop loadout, and specific details on the levels of the enemy troops.