Arcane Concentration not consumed by spell cast #165
Description
In a mage spec with Arcane Concentration, when going to the Results - Timeline, it appears as if Arcane Concentration, after it proccs, reduces the mana cost of all spells cast within the next ~11 seconds to zero. The correct behaviour would be to reduce the mana cost of the single next spell cast within the proc timeframe to zero, after which the buff should be consumed.
The bug leads to a significant overestimation of available mana in longer fights.