So I was reading through the core rulebook about critical effects and I am somewhat confused. It states that when you exceed a targets wound you inflict critical damage, is this applied after you reduce damage through toughness and AP or before? I just want to clarify this because right now it seems like criticals only happen when you kill an enemy.

After TB and AP, as usual, unless an exception applies for the damage source.

So basically when a critical is scored the thing getting critted dies everytime?

Every damage point that would have given you a negative wound point, gives a critical damage point. These are cumulative. You look up the effects critical damage on the critical damage charts. Marine's True Grit halves each freshly inflicted critical damage.

Alex

So basically when a critical is scored the thing getting critted dies everytime?

Not every time, but frequently. Many enemies in this game have True Grit, as do the PCs. After AP + (Unnatural) TB, I've seen characters take multiple hits in crits before dying.

Target gets hit.

Attacker rolls damage.

Defender subtracts effective armor and TB from damage.

Defender subtracts remaining damage from wounds.

If the defender's wounds drops (or is) below 0 the defender suffers critical damage.

Look up the critical table of the appropriate damage type (of the weapon doing the damage).

Apply the result with the number equal to the amount of wounds below zero (critical wounds) the defender currently has.

Additional damage adds to the current critical wounds (i.e. if the target is at 4 critical wounds and takes another 3 damage it is now at 7 critical wounds and applies the #7 on the critical damage table).

There are talents and traits which modify how critical wounds work, such as True Grit.

The point in this is, that you don't die from lose of wounds, you die when the effect of the critical damage says you die.

Unless it's some enemy mook, probably. I recall this was titled "Sudden Death" in the core book - I believe it was optional, but most GMs run with it as it saves time?

So, in short, Hive Tyrant gets Crits as well, but the 'Nid Warriors most likely not.

Not every time, but frequently.

One of the many reasons why I think Crit soak a la "Inquisitor" is superior to TB soak.

It may be even more of an issue in Deathwatch due to the excessive damage results sometimes rolled, be it due to the weaponry (especially when combined with various Talents) or Horde rules - this is more an expectation of mine rather than experience, though; my own group has not had a lot of fights yet.

The point in this is, that you don't die from lose of wounds, you die when the effect of the critical damage says you die.

...or you get hit by something which is designed to smash a titan to bits and then you are just a crimson mist/puddle of molten power armour without the crit table even coming into play!