Unfortunately, sacrificed heroes cannot be recovered. As Puzzle Combat is an online multiplayer game, reversing in-game content would provide you with an advantage, which wouldn't be fair to other players. The same rules apply to every player. 

Although you cannot recover your hero, keep in mind you do get an advantage by sacrificing Heroes.

Please make sure you lock all your valuable heroes by using the 'favourite hero' button. The game is designed to ensure accidental hero sacrifices don't happen.

You can save a favourite hero by:

1. Selecting Heroes
2. Selecting the Hero you want to mark as favourite
3. Tapping the heart icon on the top right-hand corner of the screen

By following these steps, you can be sure not to lose any favourite heroes in the future.