I'll use the second attack roll because of Dim Light in the Underdark.

Celus's shadow strikes at the wight and he seems to smirk thinking it wouldn't do that much but suddenly the wight screams and grabs his head obviously taking some sort of mental damage but he stays upright still.

Og you are up with the Minotaur Skeleton on Deck

Map:

Og will swing his silvered greatsword at the Minotaur in front of him, hoping to finish it off.

Attack 1: 18 Damage: 8 + 8  slashing (the 9 should be 8, accidentally added +3 instead of +2, refer to edit for rerolling the 2)

Crit damage - 10

If the Minotaur falls, Og will move to A4 and hack into the Wight

Attack 2: 19 Damage: 9 + 5 slashing

Edit: rerolling the 2 in the first attack. 5 changes to  9 + 8 slashing + 6 crit

And finish him off you did. You can still move and get your second attack. And with it, you finish off the wight.

Combat over. Post as will.

Celus keeps up the concentration on the shadowy spike surrounding his hand and points it towards the newcomer.  "Who are you, holy man?", he says, not threateningly, but more to state his authority. (Given Celus´ aasimar background and arcane knowledge i hope to recognise the radiant spell he cast earlier) 

Arcana check for recognising radiant damage, just in case: 14

Celus you recognize the spell he casted as Guiding Bolt

Og pulls the tip of greatsword out of the wight's body and cleans off the putrid remains. He still has it in hand and says to the one who aided them, "Gratitude for the assistance. I assume you have no hostile intentions towards us. Who might you be and why are you in such an accursed place?" Og sheaths his greatsword.

OOC: Sincerest of apologies! I got my account back, someone hacked me but THANK the Raven Queen they didn't post weird crap or delete anything!

Honor regards the new party member before approaching him, "Thanks for the help but what are you doing here," she asks.

"These creatures seem to be increasing in number and lethality as we descend." Griff turns to the unexpected ally. "Well struck, we appreciate the assistance. Assuming you are not here to kill us now, what brings you to this miserable place?"

Silas applauds Og with a smile. "Well done! Well done!"

He puts his mace away and turns towards Celus. "I am Silas of Torrance. A healer, of sorts. I wander to where the gods take me. Sometimes I end up in places like... well, this." Looking upward, he gestures in a circular motion.

"And, no - no ill will. I have to admit I'm happy to see you all. I've been wandering alone for a very long time. Are any of you injured?"

OOC: Jac I final my CON save you rolls for me so am I at half hit points or at 8 HP? Because if so.... uh ME! HEAL ME!!

OOC: It took 8 off of your Max HP. I already did that for you. 

You guys see two pathways. One goes straight where Silas was (you know that going forward is the enterance). And the one the rest of you can from. 

"Where did you come from," Honor asks the cleric pointing to the way they were headed before the fight began that he came from.

She will search both minotaurs and the wight for gear or magical items. 13

OOC P.S. are you doing max HP recovery as 1 long rest to stop the life drain effects and another long rest to regain my max HP?

OOC: one long rest for full recovery. You’ll resort your Max HP and you’ll be at full HP

Silas looks at Honor. "I'm afraid I'm not too familiar with this area, I've been in this forest for many days." Silas thoughtfully looks to the sky, " The gods direct me to where I'm needed."

His gazes snaps back to the group. "Have you noticed? This forest is lousy with zombies." Silas noticed that Honor seems to be hurt.

"If you like, I'd be happy to heal up some of those wounds."

"We're not in a forest, we're in the Underdark," Honor says looking at the human man with a raised eyebrow completely puzzled but his statement. "Sure I'd appreciate the help," she adds showing her wounds from the Wight's attack.

Insight on Silas 15 is he crazy or confused or both or....

"Oh of course! I speak metaphorically." Silas say apologetically.

Honor you don't see anything on the Wight particularly magical. They have their weapons and the Wight was wearing studded leather armor but its pretty nasty looking and like it might not hold up for any use much longer.

Continue your RP with Silas and then decided what you're doing next.

Silas look at the spoiler below

Og says, "I see..." eying Silas somewhat skeptically, "Silas, was it? My name is Ogoth Kinshield. We were heading in the direction where you came from before we ran into these things..." 

He casually puts a foot on the wight's head, then applies the full weight of his massive frame on it, bursting it like a watermelon. He says to its corpse, "That was for hurting Honor."

As he kicks his boot into the ground to clean it off the putrid remains, he continues to Silas, "If you know what lies ahead, then please tell us what you know."

“To be honest,” Silas says soberly, “ I’ve been on my own for a while and I am not quite myself. Forgive my eccentricities. You seem like good people.”  

Silas reaches into his pouch and produces a folded piece of paper. “I have been retained by King and Queen Sylvaranth to find thier missing child. I don’t know why you have come to this cursed place, but my errand is of the utmost importance. A life hangs in the balance.” He glances at the paper with a grimace. “Unfortunately, I was far into the wilds and this request was delayed in getting to me. I might have already lost more time than I had.”