Why did the buff/debuff I just give suddenly disappear?

The effect turn count of a buff/debuff is decreased by 1 turn at the end of an enhanced/afflicted character’s action phase.
Therefore, the effectiveness of a buff/debuff may change depending on the order of characters’ action phases.

The following examples describe situations where only 3 characters are battling.

• Example 1: When a Buff/Debuff is Given Early in a Turn
  Characters and Action Phase Order → Character A: #1 / Character B: #2 / Character C: #3
  • Turn 1, Action #1: Character A’s action phase starts
    
    • Character A gives a buff/debuff to Character B
  • Turn 1, Action #2: Character B’s action phase ends
    • The effect turn count becomes 0, and the effect is dispelled
  • Turn 1, Action #3: Character C attacks Character B
    
    • Character B is attacked without being affected by Character A’s buff/debuff

• Example 2: When a Buff/Debuff is Given Late in a Turn
  Characters and Action Phase Order → Character A: #3 / Character B: #1 / Character C: #2
  • Turn 1, Action #3: Character A’s action phase starts
    
    • Character A gives Character B a buff/debuff
  • Turn 2, Action #1: Character B’s action phase ends
    
    • The effect turn count becomes 0, and the effect is dispelled
  • Turn 2, Action #2: Character C attacks Character B
    
    • Character B is attacked without being affected by Character A’s buff/debuff

• Example 3: When a Buff/Debuff Becomes Effective for 1 Time Only
  Characters and Action Phase Order → Character A: #2 / Character B: #1 / Character C: #3
  
  • Turn 1, Action #2: Character A’s action phase starts
    
    • Character A gives Character B a buff/debuff that lasts for 1 turn
  • Turn 1, Action #3: Character C attacks Character B
    
    • Character B is attacked while being affected by Character A’s buff/debuff
  • Turn 2, Action #1: Character B’s action phase ends
    
    • The effect turn count becomes 0, and the effect is dispelled