A Heroic Public Event is a public event, in which certain conditions for the activation of an extended task have been fulfilled. For each type of event, you need to be able to react appropriately, e.g. by destroying an enemy plane, even if the purpose of completing your mission is to defend a specific point for a certain amount of time. Performing specific activities will interrupt the standard public event and replace it with a heroic one - which sets a new goal and greatly increases the difficulty level (e.g. the opponents have infinite ammo and do not need to reload their weapons).
Usually, you can do simple events by yourself, in the case of a heroic event, that is basically impossible. Completing the "extended" form of public events first of all guarantees much better rewards and a high chance of finding exotic items. Down below you will find a list of conditions, which must be met in order to activate a heroic event for each activity type.
Location: EDZ, Nessus
Turn of events: In this mission you have to vanquish the designated targets three times, while they supervise the process of extracting Glimmer from the ground. After eliminating them, you must move to the next task, which is marked with an indicator that is displayed on the screen.
Heroic version: Next to each hostile target there is a small, grey mining device. Destroy the devices before you reach the respective targets. This will make the Glimmer "spill out" into a circle. You have to stand in said circle and repel waves of enemies (and also a mini-boss) until the allied transport of the resource in question appears.
Location: EDZ, Titan
Turn of events: In this mission you have to destroy a big, six-legged robot. You attack by targeting its legs, in order for the robot to collapse, which will then reveal its core - attacking said core, for the few seconds that it is exposed, deals the greatest possible damage. You should then attack another leg, and repeat the routine until the boss is defeated.
Heroic version: In the case of the heroic version, after the robot has been knocked down for the first time, power spheres will emerge from its structure: collecting two of these and mounting them on the handles by the barriers will deactivate them, and unlock access to the Scorch Cannons. You must deactivate all three fields this way. Afterwards, a second robot for you to destroy will appear (and optionally an additional mini-boss).
Disrupt Vex Construction
Location: Io, Nessus
Turn of events: Waves of Vex will be arriving at the designated location, they will become stronger with time and you must eliminate all of them. You can allow up to 10 Vex to get to their destination, where they have to spend a few seconds (they have a white glow when they are being "absorbed"). Prevent this from happening and you will be victorious - the task is simple enough that you should be able to complete the basic version of it without any hassle, even by yourself.
Heroic version: Three players are needed in order to activate the heroic version; the players need to stand on the pillars around the central point. Soon after, a Hydra, which will become the main boss of this quest, will appear.
Location: EDZ, Io
Turn of events: A large drill arrives at the designated location. Stand by it in the indicated circle (which will be bombarded at random intervals) to intercept the device - the percentage counter is visible at the bottom of the screen when you are inside the circle. During this time you will be attacked by waves of enemies.
Heroic version: About halfway through the duration of the mission, a hostile aircraft will fire at you and your allies. Destroy it before it flies off, and you will activate the heroic event, where the Centurion boss will appear.
Location: EDZ, Nessus
Turn of events: You must defeat the great, levitating Servitor - the main boss. Every now and then (at certain damage intervals) smaller servitors will appear, which will give him an indestructible barrier, so you must destroy them first.
Heroic version: Some of the smaller servitors, especially around halfway through the duration of the mission, will not provide protection to the main boss, and so most players ignore them. If you also destroy them, the main boss will become a bit stronger and more resilient.
Location: EDZ, Nessus
Turn of events: A large ship arrives at the designated location, surrounded by an orange barrier. Enter through it and destroy 3 marked Psions, then exit the barrier for a moment and repeat the action. Then there will be a boss, whose defeat ends the event.
Heroic version: Under the barrier you will notice 7 small generators. Destroy them before the final boss arrives, in order to make him a bit stronger and increase the number of his allies.
Location: EDZ, Io
Turn of events: There is a large sphere at the location of the event. You must destroy it, but indirectly: by killing the Taken in its vicinity or by finding smaller spheres under the domes from the barrier nearby. Destroy those spheres inside (since the barrier is indestructible). When you destroy them, the main sphere and the Taken will move to another Location, where you repeat the routine. You can also combine both methods.
Heroic version: To activate the heroic version, use the second method - destroy all the smaller spheres below the domes, in order to summon the main boss of the event.
Turn of events: For this task you will need as many allies as possible. There is a ritual taking place inside the building in the middle of the map: your targets are the two levitating witches, which are surrounded by indestructible barriers. To remove them, stand in the two bright circles (guarded by the Knights), and after a while the barriers will disappear (one circle is responsible for the barrier of one witch), but only for a few seconds, unless someone is constantly standing in the circle. When both the witches are destroyed, the Wizard will appear.
Heroic version: The heroic version activates as soon as you defeat the witches. Stand in the luminous circles and destroy the two bright crystals placed on both sides of the portal at a height of a few meters. Then, a more difficult boss will appear together with more of his followers. However, you do not have much time to summon the boss, the time window appears during a wave of minor enemies, which are coming out of the portal.