Blocking an attack means that your block rating will be subtracted from the damage. All abilities will do at least 1 damage every hit, so an attack with 5 damage will still do 1 damage to your monster even if your monster blocked it and has a block rating of 10.Some abilities have penetration. Penetration is subtracted from your monster’s block rating before damage is dealt.
A blue shield effect shows that an attack has been blocked successfully. A successful block means that your monster blocked on time and that the damage taken was at least reduced by 1. Your monster can still be knocked down or defeated from the damage.
Some attacks can’t be blocked or at least not by your monster. If an attack has a higher or equal penetration rating as your monster’s block rating, then that means that blocking will not reduce the incoming damage at all. When this happens, a red shield effect is spawned to represent an unblockable hit.