Usually a desperation pick, it can be combo'd in a Graverobber Baron deck as it gives an extra ruin and inflicts heavy damage everywhere. If you plan to garauntee it, make sure to build cards with 3hp or more.
It is possible for Plaguebearer to be revived by Unholy Practitioner and strike again.
Plaguebearer can be blocked knocked out before it activates, and if it survives, may activate on another turn.
Its damage will be taken in by Sacrificial Wall.
Plaguebearer can trigger your own Collapsible Bridge.
The attack order is random, thus the infantry boosted by Mounted Guardsmen or Cataphracts can sometimes take the damage on their bonus armor before said cavalry gets knocked out.