This is and old and outdated guide. To see the updated Hero Swap Guide, check this guide.
From April 1st to April 22nd, 2023, you will be able to swap two heroes.
During the event, you can choose two heroes and swap their levels, Signature Items, Mythic Furnitures, Eternal Engravings, and T3/T4 gears. Non-T3/T4 gear worn by heroes and non-Mythic Tier furniture will not be swapped.
You must have at least one copy of a hero to swap it. Heroes that can be swapped include non-Dimensional Heroes released in 2022 and earlier. So 
Awakened Belinda, 
Tamrus, 
Olgath, 
Edwin, 
Maetria, and 
Crassio can’t be swapped.
After swapping, all heroes to be replaced in your bag will be swapped with the target heroes.
You must clear Stage 19-40 to participate. If you have not swapped any heroes during the event, you will instead receive 10,000 diamonds after the event ends.
If you want to understand the best way to use the Hero Swap, take a look at the guide below.
Tier 1: Awakened Hero
Awakened Heroes are the hardest heroes to ascend, so being able to swap awakened heroes is very valuable.
Awakened Ezizh is by far the weakest awakened hero and he can do his job pretty well even at Legendary ascension. So if you have invested on him, it is a good idea to swap Awakened Ezizh with another awakened hero.
Awakened Talene is great, but she’s not as great as the other four awakened heroes available to be swapped in this event. So it is also a good idea to swap Awakened Talene with 
Awakened Solise, 
Awakened Brutus, 
Awakened Thane or 
Awakened Baden.
Awakened Solise is the best of those four heroes, she should be your highest priority. Awakened Brutus is the second best, you should choose him if you already have an ascended Awakened Solise or if you’re already building her. Your third best option can be either Awakened Thane or Awakened Baden.
Awakened Thane is more valuable than Awakened Baden in Treasure Scramble, Temporal Rift, Nightmare Corridor, and Campaign. But Awakened Baden is the most important hero for Cursed Realm. So which hero you choose will depend on your personal preference.
Tier 2: Celestial/Hypogean Hero
The second most valuable way to use your Hero Swap is to use it to swap two Celepogean heroes.
Wu Kong is the weakest Celestial hero and the easiest Celestial hero to ascend. Swapping an ascended Wu Kong with another celestial or hypogean hero is a great investment. 
Flora is not bad, but she is also very easy to ascend compared to all other Celepogeans, so swapping her can be a good idea if you do not have an ascended Wu Kong.
Zikis and 
Leofric are very weak Celepogeans in the current meta. So if you have heavily invested in one of them, you should consider using them as your swap instead of Wu Kong or Flora.
The most valuable celepogean to acquire is 
Lucretia. 
Alna is the second most valuable and 
Haelus is the third most valuable. To see the full Celepogean ascension priority, check Stargazing priorities page.
Tier 3: Overinvested 4-Faction Hero
If none of the above options are available to you, then you should consider swapping non-awakened heroes from the four basic factions (Lightbearer, Mauler, Wilder, Graveborn).
Oscar, 
Rigby, 
Walker, 
Khasos, 
Solise, 
Seirus, 
Ulmus, 
Shemira are the worst heroes in the game. Consider using them at this event if you have heavily invested in any of them.
Check the Hero Wishlist page to see a full priority list for each of the four regular factions. That will help you to decide which hero is worth it to swap.
Also, you should consider how much you’ve invested in each hero’s signature, furniture, and engraving when choosing which hero to use in the Swap Event. Sometimes it can be more advantageous to trade a mediocre hero with level 60 engraving and level 9 furniture instead of trading an ascended bad hero with 0 engraving and furniture, for example.
To help you decide which signatures, furnitures and engravings to swap, check out the Signature Items, Furnitures, and Eternal Engravings tier lists.
