Tier protection Mechanism protects your rating when you complete Classic matches while in a group with your friends. This option is to save your tier ranking if you get killed sooner in the game.

However, do note that tier protection works only if you play the matches with your friends and it won’t work for the matches with random players.

You receive a tier protection opportunities based on your initial tier or when you reach a new tier. 
1. Rank V of each tier grants 3 tier protections.
2. Rank IV to I of each tier grant 1 tier protection each.
3. Conqueror and Ace tier grant 3 tier protections.

If your total rating falls below the lowest thresold of your current tier, protection will be triggered and your total rating will only be reduced to the minimum required to enter your current tier. You will be demoted if you have no protection left.

After triggering protections, you can earn them back by increasing your total rating (except Conqueror Tier or when you reach Conqueror from Ace).