You roll a 5 (required 8). Partial success.
 
Your party agrees to Auric Bastion’s plan. You suggest going for the diamagicite crystal first, then joining the second group when you are done.
 
Solar Flare: “When his magic returns, these proud knights should not be facing the fiend alone. I shall join them.”
 
Auric Bastion: “We will be glad to have you all at our side. Now, prepare yourselves; the time is nigh.”
 
Solar Flare: “Indeed it is. Ah, before I forget, I do believe this is yours.”
 
You get Purified Philosopher’s Stone!
 
You can barely recognize the stone given to you; where a red storm of fury once raged, a calm twilit sky now glows beneath its cracked surface. You thank Solar Flare for purifying it, and put it away safely.
 
While Auric Bastion organizes his knights into several groups — two to assault the Cathedral, and the rest to cover the city in case of a nightcrawler invasion —, you notice that Apple Basket seems uneasy. You ask him if something is wrong.
 
Apple Basket: “Uh, I reckon I jus’… I ain’t much of a fighter, y’know, and all ‘a sudden, we’re goin’ up against royal guards? I-I jus’ don’t think I’m cut out for this.”
 
You offer Apple Basket to hold onto your first aid kit, and stay at a safe distance behind you in case somepony gets hurt. Otherwise, you let him know that you won’t think any less of him if he prefers to sit this one out.
 
You give First Aid Kit to Apple Basket.
 
Apple Basket: “I, uh… yeah. I think I can handle this much. Thanks.”
 
Moonflower: “Yeah! We can do this if we all stick together!”
 
You and your friends cheer and high-hoof, psyching yourselves up, before Auric Bastion’s commanding voice pierces through the frigid wind.
 
Auric Bastion: “Attention, all units! The time has come. I will lead the group headed to the High Throne. Sir Solar Flare, you are with us. Outlanders, these three knights will show you to the crystal’s room.
 
Are all ready? Then onward!”
 
The moment the order is given, four knights kick the Cathedral’s wooden gates open. On the other side, a couple of large knights clad in black and gold armour charge.
 
Champion of the Crown: “Heretics! Stop them!”
 
The first clash is brief. With the combined might of Smoke and Solar Flare, the Champions are quickly overwhelmed. As they fall to the ground, dazed, the blue-caped paladin removes one of their helmets, revealing green glowing eyes.
 
Solar Flare: “I knew there was a vile aura about them. Beware — these knights’ minds are not their own! See that you deal them no lasting harm.”
 
You nod, then split up. You follow your assigned group to the side of the room, and down a flight of stairs to the undercroft. There, more Champions await. A dozen more.
 
Before you know it, you find yourself facing many an intimidating opponent. You manage to shove and trip some of them, but as you rear up to dodge an attack, another lands below your breastplate. The impact sends you flying backward, and knocks the wind out of you.
 
Apple Basket: “Trailblazer! Are you okay?”
 
You spend a few seconds on the ground, gasping for air, until you are finally able to breathe again. You reply that you are fine, and try to shake it off, pushing yourself back on your hooves.
 
Thankfully, your allies were swift in dealing with your assailants, buying you enough time to recuperate. Now back in the fight, you continue to push forward until a massive green stone comes into view.
 
Paladin: “There it is!”
 
With your dragon friend now leading the offensive, you defeat the last pair of Champions guarding the diamagicite crystal, and make sure that none others lie in ambush.
 
Once the area secure, you and the knights trot up to the antimagic field’s core. Each standing on a different side of the crystal, you coordinate powerful kicks until it cracks, then shatters into hundreds of small pieces.
 
Paladin: “We’ve done it! We will take care to restrain the Champions of the Crown before they awake, and see to the wounded. Outlanders, if you would rejoin—”
 
Before the paladin can finish his sentence, the sound of a massive explosion suddenly drowns everything else, and sends everyone reeling. You and your friends take cover while extremely loud rumbling follows, shaking the very foundation of the castle.
 
When it is over, you make sure that everyone is alright, then hurry back up to the main room. Through a dusty window, you see that part of the castle seems to have collapsed onto the city streets.