This thread is outdated
A turn is counted down for an effect (positive or negative) every time the affected creature makes a move (or its player presses “End turn” if it’s stunned).
This means if you’re talking about attack buffs, shields, speed buffs, evasion, critical buffs or any kind of positive effect, a turn is counted down for that effect every time the creature benefitted by the effect makes a move.
If you’re talking about Distraction, Stun, Vulnerability, Deceleration, DoT, Critical reductions or any negative effect, a turn is counted down for that effect every time the victim of the effect makes a move (or it’s player presses “End turn”, if it’s stunned).
Back before 2.0, the system was exactly the same, the only difference being that turns for shields and evasion we’re counted down every time the shielded/dodging creature’s opponent made a move.
This means that Instant Invincibility Taunt can block more than 1 attack while only lasting for one turn, if the user is slower than the opponent. If the shield was changed to still last for 1 turn, but only block a maximum of 1 attack as opposed to the current 2, I’m sure everyone would be happier with the state of affairs.
It is important to note that the old concept of a turn with respect to shields and evasion is not the same as the the new concept of an “attack”. Only moves that deal direct damage are counted as attacks, even though non-damaging moves as well as manual swapping used to count as turns for shields and evasion in 1.14.
Also, counter-attacks count as attacks. This is why it is possible for an opponent to attack twice while only carrying out one turn.
Please try and spread this information as widely as possible, it will save a lot of people a lot of trouble.
Even in 1.14 there were players that thought that turns worked like rounds, where both the player and the opponent have to make a move for the turn to end, but that is not at all the case, it works more like Chess, or Monopoly, or the card game UNO.
This isn’t what this thread is about, but it’s worth mentioning that the recent update to Instant Invincibility Taunt was merely a correction, since the move was blocking more than the 2 attacks the move description promised, both in raids (shout-out to @OrigamiRobot) as well as the arena (shout-out to @Detonatress), in fact, it was blocking up to 4, as the official announcement stated. While it blocks less than before, it still blocks 2, which is arguably overpowered.
@OrigamiRobot is welcome to share their graphic representations of turns. Also, to all the forum users that bothered to stop to explain how turns work, you know who you are, you can give yourselves a pat on the back for trying to accomplish what can sometimes feel like shouting into the void.