Please help me with encounter ideas for my next session

[The Cats]

I've had some bad writer's block and our game is on Saturday so I appreciate any help.

The party wants to get into a chamber that contains a bunch of powerful giant warriors in stasis and the artifact that can be used to awaken them. They have the ingredients for a ritual to give their cleric control of the warriors and use them to fight the BBEG's forces.

The chamber is a tall cylinder that was buried beneath a fey-enchanted forest (the party is friends to the fey as they both want BBEG's forces out of there). The warriors are embedded in the walls and the artifact is at the bottom. It's not attached to any bigger system of ruins, just a standalone chamber.

BBEG's servants found it first. A battalion of his stone and hill giant army ravaged the woods and dug up the cylinder (so its at the centre of a big, dug-out pit).

The party knows there are a bunch of giants as well as an enslaved young blue dragon guarding it but there could be other servants they don't know about.

BBEG is a powerful wizard currently trapped in his own pocket dimension. The leader of the battalion is also a powerful stone giant wizard. The party has had plenty of run-ins with the giant battalion already. They ended last session after causing chaos in the battalions main encampment, unleashing several big mean monsters all at once, then fleeing into the woods. The chamber is in a separate location but travel is no problem thanks to their alliance with the fey.

The party has been really embracing the idea of trying unorthodox methods and trying to get full use of their abilities and stuff to do clever things so I'd like to give them the opportunity to do that but all I can think of right now is a big brawl with giants and the dragon at the front gate. Please help!

[Bohandas]

How about some fey that's disasterously incompetant at being helpful

[Elvensilver]

Blue dragons are supposed to be manipulative, right? And they can burrow - so how about the dragon dug a secret tunnel that ends just short of the lower end of the cylinder (so it isn't an easy way to bypass the encounters) when they forced him/her to help digging.

Now the dragon secretly turns to the party for help to get free from the giant army. In exchange, he/she tells them about the tunnel and promises to turn against the giants when possible.
Of couse, a young blue dragon probably has a hidden agenda, too...

This ally and the tunnel should give the PCs additional opportunities: collapsing the tunnel to create difficult terrain or turning the dragon and the giants against each other the least of them.

[MarkVIIIMarc]

If the party hasn't fought one of theae would be allies, maybe set one up as a defender of the rest? Movies do well with bad guys turned good (Terminator) and anti heroes.

Golems are good guardians also. Ropers seem a natural for less refined places.

What level are your party members?