Ebony

The Emperor Tree clearly tried to imitate the mechs employed by the invading humans.

There was a clear distinction between different generations.

The basic wooden mechs and the elite purple wooden mechs already granted the calamity plant a lot of versatility on how to handle a lot of threats.

When that did not prove enough to stop the most powerful human mechs, the Emperor Tree decisively invested more effort and resources to produce a small selection of the champion ebony wooden mechs.

The latest wooden constructs already demonstrated their power.

Just one of them was able to wear down the Promethea's resonance shield by a considerable extent with fast attack runs.

It was also able to attack from a distance as it apparently wielded a luxurious version of a seed cannon.

That made this enemy unit a lot harder to deal with as it was able to attack at any distance.