Suggestion to donate heroes
As known in the eagle artillery, each hero is 25 housing spaces.
So the suggestion is to donate heroes to clan castles, which occupies 25 housing spaces as well.
The donation upgrade perk applies, so if you donate a level 30 BK in a level 10 clan, he becomes level 32 BK.
The donation refund perk also applies, but in a different way.
In a level 1 clan without this perk, you can only donate a fully healed hero, after that he will sleep for the full amount of time.
In a level 3 clan, the donation refund perk is 20%, so you can donate a hero if he has 80% or more HP. For example, if you donate a hero with 90% HP, he will have 10% HP left, but the receiver will receive a full health hero.
In a level 9 clan, the donation refund perk is 50%, so if you donate a hero who has 70% HP left, he will be left with 20% HP.
The hero in the clan castle uses a different way. He doesn't automatically regenerate health.
For example, if during a defense or offense, he gets hit and his health is reduced to 50%, then at the next offense, you can deploy him but starting at 50% HP, or at the next defense, he will defend the village but also starting at 50% HP. If his health reaches 0%, he will disappear from the clan castle, and you can request for another hero. Also, if you have used his ability, you can't use the ability again in the next match.