(@LST Sunforger, you do get advantage on the saving throw however since you took the dodge action.)

(Ah, don't have that supplement.)

Dex saving throw: 21

Con check: 8

(Are you serious.  You can't be serious right now.  Please tell me you're not serious right now.)

(@LST At least you now have 2(or was it 3) nat20s under your belt?)

(3 total, now.)

Og looks somewhat confused as his darkness is dispelled, but then reinforces his armor with an additional shield.

He'll then move to M8, and chuck a javelin at Roth.

Attack: 28 Damage: 8

Rothander stands his ground as the javelin glances off his armor. Calling his hammer back to his hand as he moves to L8. "Well, lad lets get ta swinging. I'll let ye go first."

Gell's Farm Round 2:

Both contenders move into position, and then Rothander suddenly yeets his warhammer at Og, who expertly dodges the worst of the explosion but loses focus on his aura of darkness.

Og, slightly irritated, steps forward to launch a javelin at the dwarf, but Rothander is essentially a walking fortress and the javelin bounces off his armor, leaving him unscathed.

(Rothander is up)

  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P
16  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 =====================.......====================
15  .  .  .  .  .  =  %  %  .  =  .  .  .  .  .
 ...............=................................
14  .  .  .  .  =  .  .  /  =  =  =  .  .  .  .
 ...............=.................=..............
13  .  .  .  .  .  =  %  %  %  =  .  .  .  .  .
 ................................................
12  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 ...............===================..............
11  .  .  .  .  =  .  .  .  .  .  .  .  .  .  .
 ...............===================..............
10  .  .  .  .  =  .  .  .  .  .  .  .  .  .  .
 ...............===================..............
09  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 ................................................
08  .  .  .  .  =  .  .  .  .  .  . R. M.  .  .
 ...............=................................
07  .  .  .  .  =  .  .  .  .  .  .  .  .  .  .
 ...............=................................
06  .  .  .  .  =  =  =  =  =  =  =  .  .  .  .
 ................................................
05  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 ...............=................................
04  .  .  .  .  =  .  .  .  .  .  .  .  .  .  .
 ...............=........\.......................
03  .  .  .  .  =  .  .  .  .  .  .  .  .  .  .
 ...............======%%%%...======..............
02  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 =====================.......====================
01  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P

Key: '=' Stone wall (15 ft), '%' Door, '/' Lever (Has a small note saying "Pull me :)" on it)

(If that was Roth's turn,)

Og excepts the angry dwarf's rush with glee, and marks him for destruction.

Attack 1: 17 Damage: Nada.

Attack 2: 28 Damage: 9 bludgeoning and 28 radiant.

(No booming blade since I have Extra Attack now.)

(Well, that was underwhelming.)

(Crit fishing was probably a bad idea, given my luck.)

Gell's Farm Round 3:

Rothander summons his hammer back to him and strides into melee.

Og graciously accepts the dwarf's invitation, cursing him and swinging twice. The first attack is easily blocked, but the second manages to pierce all seventy-four layers that Rothander is wearing and blast him with divine energy (DC 15 Con save to maintain SoF, Rothander)

After Og strikes Rothander, the arena shakes and dust begins to spill from the ceiling. A quick glance upwards reveals that the stone above the arena has cracked. As dark lines spiderweb across the stone, it shatters and falls to the floor, crushing various parts of the arena. The floor in the middle of the arena breaks under the weight of the stone, revealing dark water below. Our competitors are unharmed, and battle continues.

(Rothander)

   A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P
16  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 =====================.......====================
15  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 ..................++++.....++++.................
14  .  .  .  .  +  +  + G.  +  +  + .  .  .  .
 ...............+++++++.....+++++++..............
13  .  .  .  .  +  +  +  .  +  +  + .  .  .  .
 ..................++++.....++++.................
12  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 ...............~~~~~~~~~~~~~~~~~~~..............
11  .  .  .  .  ~  ~  ~  ~  ~  ~  ~  .  .  .  .
 ...............~~~~~~~~~~~~~~~~~~~.....++++.....
10  .  .  .  .  ~  ~  ~  ~  ~  ~  ~  .  .  .  .
 ...............~~~~~~~~~~~~~~~~~~~..............
09  .  .  .  .  ~  ~  ~  ~  ~  ~  ~  .  .  .  .
 ...............~~~~~~~~~~~~~~~~~~~..............
08  .  .  .  .  ~  ~  ~  ~  ~  ~  ~ R. M.  .  .
 ......++++.....~~~~~~~~~~~~~~~~~~~..............
07  .  .  .   .  ~  ~  ~  ~  ~  ~  ~  .  .  .  .
 ...............~~~~~~~~~~~~~~~~~~~..............
06  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 ................................................
05  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 ..................++++.....++++.................
04  .  .  .  .  +  +  +  .  +  +  +  .  .  .  .
 ...............+++++++.....+++++++..............
03  .  .  .  .  +  +  + G.  +  +  +  .  .  .  .
 ..................++++.....++++.................
02  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 =====================.......====================
01  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P

Key: '.' Stone Floor, '=' Stone wall (15 ft), '+' Rocks (10 ft), '~' Water (10 ft deep)

As Rothander takes the damaging blow he feels he's fighting spirit coursing through his body. He takes two swings with his new Warhammer. 

Attack: 18 Damage: 12

Attack: 21 Damage: 8

Con 20

(Just a heads up, Og, Great Weapon Fighting doesn't allow you to reroll smite damage, only the weapon dice)

(I've been rolling it this way as BDaddLy's ruling.  I asked him before I even got the Fighting Style.)

(Also, both of those miss.)

Og goes for another round of attacks.

Attack 1: 29 Damage: 11 bludgeoning (waiting to roll smite damage for a ruling on GWF)

Attack 2: 17 Damage: Nil.

(The bludgeoning damage in my previous turn should actually be 10, I added the wrong modifier.)

(You still have to roll for mirror image for both attacks, however)

(The relevant ruling for GWF is found here)

(I'm aware of the ruling, BDaddLy just ruled it differently.)

Mirror Image rolls: 7, 10

(This was what he said about it:

"Yes, you can re-roll the smites. There will probably be some push back, but it is not game breaking at all. Particularly because I like math.

1d8=4.5 1d8ro<3=5.25

the feature adds .75 average damage per d8 when you smite for 5d8 with a 2d6 great sword it'll increase your average damage by ~5 hit points.")

(Right, it doesn't add too much damage, but from my point of view it doesn't make much sense that being better at swinging heavy weapons means that your divine powers become more powerful/consistent)

(Ok, but that's a little unfortunate.  Not sure I would have gotten that Fighting Style if he hadn't ruled that way.)

Divine Smite damage for earlier: 16

1d8+10

As Rothander takes the hit he starts to cough up a little blood. He takes a moment and catches his breath and assumes a defensive posture calling upon his dwarven fortitude. Looking better than he did a couple seconds ago he looks at Og "Lad tha was a good hit."

Second wind 11

Dwarven Fortitude 20

Con 16

Og will take the opportunity offered to him to attempt to snatch Rothander's shield from his grasp (if he can do that).

Athletics?: 15

If not: Og will continue the pain train.

Attack 1: 20 Damage: Nil.

Attack 2: 13 Damage: Even more nil.

(And yes, I did factor in the disadvantage.  It just removes the advantage my Oath of Enmity gives me.)

(Also, SoF is down now, correct?)

(DC was 13 adding up from that last attack. But Roth is pretty tank.)

(I will be disappointed if the danger at round 4 isn't some kind of canine like creature.)

"Good try lad" as Rothander deftly sidesteps the two slashes of the great sword. He then once again feels his fighting spirit and starts into a barrage of swings with his Warhammer still trying to get used to the new weapon. 

 Attack: 17 Damage: Unable to parse dice roll.

Attack: 29 Damage: 11

Action Surge

Attack: 22 Damage: 7

Attack: 26 Damage: 11

Athletics 6

(The attacks are only if I can't do the athletics.  I'm guessing that would be a full action.)

Concentration x2: 7, 7

(I'm just done at this point.)

Recasting shield of faith.

Attack 1: 30 Damage: 12 bludgeoning and 15 radiant

Attack 2: 20 Damage: Nil.

Smite damage should actually be: 14

(I used d6s . . .)

(OH FFS!)