Мафия 85. Lux in tenebris

I don't quite understand the purpose of the Hydra's Provocation ability.

It's meant to allow the Hydra to grow additional heads. The idea is this: initially, the Hydra has two heads and is charged with one unit of energy. Let's say, over some time in the game, the Hydra accumulates two more units of energy, but no one attacks it. Then, it uses Provocation: on one hand, it attacks, and on the other hand, it is attacked. As a result, the Hydra loses one head, but it quickly regrows it, and also gains an additional head.
In general, Provocation is a safeguard against the situation where the Hydra is left untouched for a long time, and then is quickly calculated and destroyed.