Unfortunately i cant find original thread of it ( i see it was locked), where lady of the lake was cutting mana with my Baldur special activated.
This time it happened to the left two heroes (Tyr, Baldur) from Mitsuko. As you can see, two out of three of my Baldurs have mana prevention special on, yet Tyr and Baldur lost mana (all the rest heroes have practically similar mana)…
In comparison JF is fast and Tyr is fast and see the mana difference 
Maybe there is bug if multiple Baldurs have special on? Having multiple Baldurs is not very often, so my situation is rather rare.
