best way to kill a champion in DR

An announcer shouts, "Round 5, send in a champion!"  An iron portcullis is raised and a robust goblin champion enters the arena!
>watch champ
You appraise the situation and notice the goblin champion may push you into a lit torch, you could try to duck down!
>duck
You set yourself up to duck out of the goblin champion's way!
>beseech sledge
You beseech your elven sledgehammer, causing violet flames to spring to life around it!
>qstr 3
You prepare yourself to strike quickly on your next combat action.
[You will attempt to perform your next combat action in no more than 3 seconds.]
>aim chest
You're now aiming at the chest of your target when using a ranged weapon, or while ambushing.
>ambush
As you attempt to strike with your elven sledgehammer, it sends a surge of power through you that quickly leaps out at the champion!
A pillar of crimson radiance manifests around a robust goblin champion.
  CS: +418 - TD: +303 + CvA: +8 + d100: +72 == +195
  Warding failed!
You feel the unnatural surge of necrotic power wane away.
  Waves of sacred energy tear through the goblin champion's body!
   ... 38 points of damage!
   ... 60 points of damage!
   Blow cracks a rib and punctures a lung.
  Breathing becomes a challenge.
   The goblin champion is driven to his knees!

You swing a massive elven sledgehammer at a robust goblin champion!
  AS: +694 vs DS: +417 with AvD: +41 + d100 roll: +58 = +376
   ... and hit for 213 points of damage!
   Massive blow smashes through ribs and drives the goblin champion's heart out the back.
A robust goblin champion breathes his last gasp and dies.
Roundtime: 6 sec.
Roundtime changed to 3 seconds.
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