I know this sounds silly ahahah lol But I've been looking for how I can "burn" players when I put a commando, I have a clue but I don't know if it's that, someone could help me? I'd appreciate it.
Learn to read the source code https://github.com/pmmp/PocketMine-MP/blob/stable/src/pocketmine/block/Fire.php#L75.
that was a pretty bad way of doing it unless you wanted a fire block to spawn where they were too. Mark this as solved.