That’s exactly the bug that the OP was complaining of. Looks like we need to do some collective testing to isolate the problem, or understand why it isn’t a bug.
Update: just ran a raid and counted tiles. Everything looked fine using Alberich, Magni, Sartana, Tibertus and Merlin.
That’s because defense heroes gain mana differently than the offense.
- on offense, a hero only gains mana by matching tiles (unless boosted with a gain-mana buff from, say, Alberich). You gain one tile’s worth of mana when the tile hits a foe, or two tile’s worth if it “ghosts” (doesn’t hit a foe). Certain troops or specials increase the amount of mana each tile is worth.
- on defense, every hero gains a tick of mana each turn. Any hero hit by a tile will gain a chunk of mana; the chunk size decreases the more tiles hit in a particular turn (so a huge cascade may not charge all foes’ mana). Again, mana-boost troops and specials may increase the mana gain.