Mafia 75. The Mystery of the Ancient Ruins.

In my opinion, the night defense is a bit weak. Maybe it would be better to have full protection? Or 50%?

I think that 25% is optimal. Because if you reduce 50% or all of it, you use poison, send in the Silencer, and that's it – no defenses will matter at all. And the Cartel is already strong in terms of killing, plus there are more of them.

Oh, and another thing – how many night defenses does the Mafia have? Two or three? Does the ultimate ability count as a separate night defense?

I've added the information to the post with the Mafia teams.
Three, but one from each role. The Cartel has 2, as soon as Damien dies.
The ultimate ability is different for the two Mafia members.

And also, in one Mafia team there are three Mafia members, and in the other, four, and I didn't see any significant advantages for the three-Mafia team that would justify the size of their team, and no, strong defenses can hardly be considered as such.

Strong defenses, considering that the second Mafia members don't have the ability to break natural defenses, is an advantage.
Plus, one of them is completely immune to magic.
And the Guard has a block, and we all know how that nasty thing can ruin plans.
But, again, let's see. If the players notice this, we might strengthen them somehow. But I think they're already overpowered.