<Posting as Tuksen Saguaro>
All pleasantries aside, you've obviously lost possession of your faculties. Asmodeus sees all, knows all and will not take kindly to you abandoning his counsel for these demonic problems you've had of late. If you were a true Chelaxian, which is as plain as the lash above your bed that you are not, Asmodeus would have found the right contract for you. To deny Him the opportunity is to spit in His face. He's the rock to whom you should have turned, yet you cast Him to the docks like one of your used slips.
I find no further need for your correspondance, as I shall not sully myself by being associated with a traitor to Cheliax and, more importantly, a heathen to Asmodeus.
May Asmodeus guide my blade,
Reason I suggested alternate tactics, is that he is physically unable to follow the tactics as listed. He does not have haste memorized, (and as far as I know), he has zero way of casting it. It's also an opposition school for him, so even if he had an arcane bond, (where nowhere it mentions this), he cannot cast opposition schools from it, thus his tactics as written are invalid.
A DC 5 perception check (once the PCs are in the building) gives them all the time in the world to prepare for the coming storm.
Welcome to the club! The Guide to Organized Play (free download) would be a great place to start. It outlines what is legal/not legal, what resources you need, etc, etc. The Core Rulebook along with the Guide to Organized Play are considered Core Assumptions. You may create a character using material form those sources without needing to have them at the game table.
If you wish to use any other material from other books, you must own a copy of that resource. Physical or PDF and you must have it at the table. Players are not able to use the PFSRD as a legal resource at the table.
I understand the initial hesitation of joining PFS. I, too, was originally of that mindset. Howver, IMHO, what it loses in those personable things as well as some restrictions in items, archtypes, races, etc, it more than makes up for with great stories and the fact that you can simple show up and play. No need to try and schedule a game around 6 people's lives. Just show up and play. If you can't make it one day, it's no problem.
Roleplay is still encouraged, as well as creative solutions, though you don't necessarily have the same sandbox in which to play. There are thousands of great people with whom to play from across North America (and the World!).
One last great point. When you go on holiday, bring your characters with you. You never know where you might be able to squeeze a game in.
Best of luck and again, welcome!
Then it seems to me that Tancred's best course of action would be to use his SA Invisibility once he notices the PCs in the building, followed by True Seeing. They last for some time, probably more than enough for them to still be active when the PCs come knocking, and he knows they will.
He's squishy, so he needs some meat up front once things get nasty. Use his Summon Demon Special ability, follwoed by Summon VI for perhaps a Huge Ice Elemental or Shadow Demon to control some space (chosen based on what PCs he sees, since he's not stupid. An evil creature vs. what appreas to be a Paladin is just a bad choice). As a conjurer, his best bet would be to remain invisible, summon a few critters that are immune to cold and able to keep the PCs occupied, then when the time is right, blast away with his Cone of Cold, using his Demonic Mark to cast it twice.
But since the best laid plans never survive the first volley with an enemy, that could be all for not, though there should be enough on the field initially to give him that time to make the PCs lives miserable.
Suggestion for the future. I know it can be difficult, as many players want to play, but where possible, run seasons 0-3 with only 4 players. They're geared for that many PCs and running with extra can make it a day in the park.
You might consider some different tactics, especially in regards to a Bearded Devil.
I know you didn't hit them at all, but, in the end, sometimes, that's the way the dice roll.