If Darius Executioner gives +1 might to other friendly units, can Fiora tap to channel an exhausted rune when a 4-might unit is played (since it becomes 5 might)?

Ruling: No, you cannot tap Fiora to channel an exhausted rune in this situation. Darius's passive applies immediately to the incoming unit, so there is no moment when the unit is not 5 might.

Sequence:

• The unit enters the board
• Darius's +1 might passive applies immediately
• The unit is 5 might with no window where it was 4 might

Nuances:

• This differs from Shen's interaction with defender designation. When Shen is played as a reaction to defend, there is a window between entering the board and gaining the defender designation where his shield passive is not yet active and he is only 3 might.