"Also, if he really wanted to build an army, the better strategy would have been to send thralls like the Treantling-Grendel you've faced and infect only the most powerful plant folk instead of random people.
"It would have taken time, but undead can wait. Consider that most plant folks wouldn't reveal being infected in fear of being shunned or considered a traitor. All of this mess, even involving the three great Countries, is too dangerous even for Erlik himself.
"Not only did he make himself an enemy out of the entire continent, but even in the case his plan succeeds, Erlik will never be able to feed so many mouths. Undead are many things, but stupid isn't one of them.
"The stupid ones never live long enough to become this dangerous. Undeath is something that cannot be spread carelessly, especially now that the human population has been dramatically reduced.