1899h, 3624m, 3654e, 10p, 13474en, 20420w exbp---/02:33:34.125/ (H: -253)
With a focused look, Luthe strikes at you with an icy steel hammer. Your left
leg is smacked with a force that goes to the bone.
You blink for a moment, then instantly, all about you is darkness.
1694h, 3624m, 3654e, 10p, 13474en, 20420w exbp-
Chanting dark words Ethelon points twords you, sending a shiver up your spine.
1694h, 2594m, 3654e, 10p, 13474en, 20420w exbp-
The shadows weigh on your thoughts, draining your mental energies.
1694h, 1564m, 3654e, 10p, 13474en, 20420w exbp---/02:33:34.406/ (H: -205)(M: -2060) erm
You look up into the air for divine inspiration.
1694h, 1564m, 3654e, 10p, 13474en, 20420w exbp---/02:33:35.359/ diag

You are:
succumbing to Mother Night.
suffering from a pierced left arm.
blind.
paralysed.
1694h, 1564m, 3654e, 10p, 13474en, 20420w xbp---/02:33:37.296/
The shadows weigh on your thoughts, draining your mental energies.
1694h, 534m, 3654e, 10p, 13474en, 20420w xbp---/02:33:37.656/ (M: -1030)

Mana   : 4304/4304     Willpower : 20420/20420

In three seconds, that's over 3k drain.  That's INSANE.  Even without the double hit, that's 2k.  Succumb is to Lash as Haymaker is to freaking newbie kick. 

Succumb really is My favorite skill, most evil yet weak thing I have ever coded.

There is a hidden defence against it, that can make it just slightly weaker than lash.

Succumb drains me for 350 mana every 4 seconds, and only hits me once before I cure it, so I must be doing something right.

3998h, 4448m, 4223e, 10p exk-
Your fighting stance is defending your legs.
You are fighting with powerful blows.
You are a lich.
Your body is prepared for lichdom when death comes for you.
You are filled with the greed of Acquisitio.
You are filled with the wrath of Rubeus.
You are filled with exuberance.
You are surrounded by numinous dragon scales.
You are reaping the gifts of Fortuna.
Your blood is clotting by virtue of the Ray of the Kingdom.
Your ego is regenerating by virtue of the Ray of Beauty.
Your mana is regenerating by virtue of the Ray of Perfection.
Your health is regenerating by virtue of the Ray of the Merciful Hand.
Your body is prepared for a marathon workout.
Your muscles are flexed for increased strength.
You are surrounded by the Geburah Sphere.
You are surrounded by the Netzach Sphere.
The pull of the earth roots you more firmly to the ground.
Your actions are cloaked in secrecy.
You are bathed in the glorious protection of decaying flesh.
Your body is weathering the storm of life a little better.
You are regenerating lost health.
You are resisting magical damage.
Your vision is heightened to see in the dark.
You are using your superior constitution to prevent nausea.
You are maintaining consciousness at all times.
Your regeneration is boosted.
You are lipreading to overcome deafness.
You have insomnia, and cannot easily go to sleep.
Your insides are warmed by a fire potion.
You are feeling quite selfish.
You have ingested the kafe bean and are feeling extremely energetic.
You are concentrating on maintaining distance from the dreamworld.
You are tempered against fire damage.
Your mind is sensing the death of others.
Your hands are gripping your wielded items tightly.
You are viewing the world through the third eye.
Your sense of time is heightened, and your reactions are speeded.
You are protected from hand-held weapons with an aura of rebounding.
You are sensing distruptions in the aether.
You are protected by 40 defences.
3998h, 4448m, 4223e, 10p xk-

Succumb drains me for 350 mana every 4 seconds, and only hits me once before I cure it, so I must be doing something right.

Yes, you do have succumbs only weakness.