Pohatu never had a heart. Instead of saving Ketar, he left Ketar to be killed by Umarak, grabbing the Mask of Control. Umarak tried to take it back, but the other Toa arrived, fighting off the Shadow Hunter and carrying the wounded Pohatu and the Mask of Control back toward the City. On the way, Umarak attacked again. In order to fight him, Tahu donned the Mask of Control.
It didn’t end well.
The concept of a corrupt Tahu is a clever one at the least, though I recommend that you would add some other armor pieces in the “uncorrupt” part of this Tahu moc
Bold of you to assume I still remember how I made this thing.
Also, wow, this post made me realize G2 was 8 years ago
But yeah, I’m pretty sure it’s the same internal build as Tahu Uniter. The only thing I did was move the armor pieces around, add some masks and a foot, and swap the head and hand piece.