It uses very high anti-squat paired with a very low leverage ratio at the beginning of the suspension travel. It means that pedalling extends the suspension, and it can maintain itself at zero travel with a rider's weight on it. The wheel path is quite rearward at the beginning of the stroke so it activates well when it encounters a bump.
It has a high amount of pedal feedback through all of the gears, so this will be noticeable, particularly under hard braking where the freehub will engage if you strike a bump at speed with the wheel locked. It's similar to other high anti-squat designs. 2015 Norcos, etc.
The leverage ratio increases through the travel, which is the exact opposite of what most riders consider to be ideal. Rather than have an increasing spring rate as you go through the travel to achieve good bottom out resistance (usually referred to as a "progressive" design), the tantrum is very regressive, meaning the bike is very easy to bottom out. The guy at tantrum recommends fixing this by packing the air shock full of volume spacers, but this upsets the damping and is hard to tune.
It's not for me, but some people like it.