I want a dragon to do this:
Roused from his slumber by the incautious footsteps of the adventurers, the scaled beast pushes itself to its feet, the gold and jewels of its hoard scattering from its wings and beneath its talons. As the dwarven knight rounds the corner into the cavern, the wyrm roars and draws back its clawed foreleg, then swipes in at the charging warrior. The knight's shield blocks the worst of the blow, but the dwarf is staggered and his axe fails to pierce the dragon's scales.
The dragon picks out the arcane words of a spell being cast, and then a slender wizard peeks his head around the corner, trying to sap the dragon's strength. The beast struggles for a moment against the magic, long enough for a cleric's smiting word to shatter a small expanse of scales across its shoulder. From a darkened corner of the room, an arrow flies and embeds in the chink in the dragon's armor.
Furious, the dragon takes a half step back, batters the knight with a pair of claw swipes to reel him and bruise him within his metal shell, and then snaps its head forward to chomp onto the dazed knight's shield arm. The two struggle for a moment as the dragon rips away the warrior's shield, but before he can escape the dragon scoops him up in his teeth. The knight screams defiantly and begins hacking at the dragon's face, scoring a lucky blow against the beast's eye.
The wizard unleashes a fusillade of magic missiles, their arcane force completely bypassing the monster's armored hide. The cleric rushes in to aid the knight and shouts a quick spell of healing, but his mace strikes upon the beast's legs barely faze it. The hidden archer once again lands a strike in the weakened spot, though, and the dragon snarls in frustration.
Annoyed with these tiny foes, the dragon rears up, then smashes a claw down upon the priest, crushing him and pinning him to the floor. Then it coughs a lick of flame onto the knight, setting his hair and beard alight, before whipping its head sideways to fling the knight as a projectile. The hidden archer cries out as the knight smashes into her, sending them both tumbling to the floor. The flaming dwarf clearly illuminates the annoying sniper, and the dragon ponders which foe to kill first.
The knight rolls to put out the flames searing his face, then staggers to his feet and charges. He swings his axe in both hands, but the dragon turns its vulnerable side away and gives a raspy chuckle as the mighty attack barely chips its flank. The wizard boldly advances to be within range when he casts a cone of icy cold, and this does enrage the dragon. The chill weakens its scales for a moment, long enough for the archer to dig another pair of arrows into its hide.
On the ground, the cleric struggles to break free, but can't. Nor can he cast any spells.
Keeping one claw planted on the cleric, the dragon pivots its whole body to lash its tail. The wizard, and the knight he thought he was safely hidden behind, are lain out onto the floor, digging short divots in the treasure horde. Then, like a child taking his plaything over to a new game, the dragon grabs the cleric and launches itself through the air. It flaps its massive wings twice to build up speed, and swoops toward the perilously solitary archer.
And no, it hasn't even breathed yet.
Big monsters need to be able to dominate the battlefield with their size and strength. Whatever magic powers they have are just icing on the cake.
Also, dragons should be hard to injure at all (AC as good as a knight in armor with a shield), but certain attacks should be able to create chinks in their armor.
