Plants do near 0 damage against bone tyrant

The giant skeleton named the bone tyrant that climbs out of a pit, that appears at the end of some maps appears to drop vines off the moment they apply.

I have been fighting one of these bosses with my plant sorcerer for about 5 minutes and it is almost dead but most of the damage I've done was from lightning storm and the occasional explosion from overgrown plants.

I uploaded a video of the final few percent of the fight just to illustrate it.

https://youtu.be/57MF3nbQi9k