Well to start off you need some context, I've been running a game now for nearly 11 months now and my party is level 17 and last session the wizard betrayed them, this is not the issue in fact this was planned by both of us for about 6 sessions now and the execution was beautiful as the wizard left the other 4 in dimensional shackles and teleported away as the entire tower began to collapse and lava begin filling the lower rooms and... well you get the point the wizard betrayed the party and they escaped with the dimensional shackles still on them so they couldn't really teleport back to their base where the wizard was right now and decided to make that journey on foot which takes them about 3 days and the BBEG informs the wizard that they are coming after him
The session ends and the party is talking to themselves and such and I say all of them get 3 days of preparations and so the other 4 decide to leave the room to talk and the wizard and i am alone the conversation goes something like this
"Do you want help?"
"With what?"
"The fight obviously."
"Nah, I'll just start using some of my stronger stuff before I lose to go out with a bang you know."
"What?"
"You know just to stop holding back a bit"
"Dude you have the lowest DPR in the party."
"Brother Thats because i was playing support."
"Prove it"
"I thought I was supposed to lose lol"
"And you will"
"Welp alrighy then"
And this was my horrible reenactment of the conversation 4 days ago and since i dont have perfect memory I got many of the details wrong but the main thing is basically he said he didn't need any backup from the BBEG and take on the other 4 party members for a better final stand (which btw are a wild heart Barbarian/ A light cleric/ A thief rogue/ and a draconic sorceror with a one level dip in warlock) I said he couldn't and its not like he's a minmaxer like I know this guy.
So I tell the party to send what they will be doing for the next three days on discord as the next sess will be starting with them arriving back to base with vengeance in their hearts
They all send me their plans and then its the wizards turn and well uhh.... this is what he messaged me.
So I'll just start spamming glyph of warding and storing spells on the pedestal in the center room
Expeditious Retreat/Longstrider/Mirror image/Elmisters Elusion/Blink/fly/haste/Stoneskin/Blur/Greater invisibility/Alustriel's Mooncloak/Telekinesis/True Seeing/Simbul's Synostodweomer/Conjour minor elementals (8th level)
With all the glyphs activating once I hug the pedestal and then I take a lr and wait for them to arrive
...and yeah now I am in a lot of trouble and now I could go to him and say he was right and he would probably agree but I hate the smug look on his face, i dont really want to tell the others his plan cause that would be unfair and railroady since they should have no way of knowing
Soo I do need advice I do think the party might be somehow able to pull off a miracle and which should help and there is a way for them to make this easy that is if the cleric casts antimagic field and grapples the wizard so maybe this isn't too unfair but what do you all think
Edit#1 guys the betrayal was not a secret literally every player knew their characters did not though heck they all got the offer by the BBEG at the same time and only the wizard accepted and in those 6 sessions the others made sure to guilt trip him these are some quotes from those sessions (and yes we keep track of quotes)
The cleric who is a very old grandpa: Ah Im getting to old for this crap... well at least I know I'll always be able to count on you Eh sunny.
Also the cleric: I dont have much time left but I ain't plannin on dyin before I see you and Samanda together kekeke (PS Samanda is the clerics granddaughter who is engaged to the wizard)
The child Barbarian who wields a club made of sugar: Hey big bro after we're done here will you take me flying again pleaseeee your magic is fun to play with.... Really!! Thanks big bro your the best.
And the rogue with a very traumatic backstory: After all that I never thought I would every be able to trust again... well that was until I met you all even you Es (wizard nickname) before she gives him a hug
And the sorceror well he didnt do much but still anyway the point is this was something gone through the table alright the fight was supposed to happen and as for what happens after even I dont know the others could forgive him or not no idea its their choice
The wizard betrayed em because well obsessed with magic and the BBEG promised spells beyond their greatest dreams
Anyway I've decided to just let it happen and ill keep you all updated