I was approached with this story.
A friend attacked a team in war of only 1 maxed onatel and she felt like her mana was accelerated with out her special affect even being on.
I know this is a thing for each dead hero on defense the amount of mana gained for the rest increase.
I can’t find it anywhere in the forum or guides and war isn’t on so I can’t check if it says it in game in any way. But I know it’s a thing maybe unwritten rule?