Right? I think my favorite combat my players ever prepared for was 'the teleport-capable scout has seen an enemy witch and her kill team coming this way on a giant summoned ice worm.'
Obviously, stand-up fighting a mage and squad of unknown attendants riding a giant summon is bad times, so a plan is required.
The party mage considers what she knows about things like this and comes to a few conclusions. 1: It definitely has an extremely dangerous breath weapon. 2: It has no eyes, so it must hunt by body heat or something.
She contributes a set of alchemical heat packs to distract it, and an hours work with a simple shape earth spell to make an encirclement of three foot stone spikes.
Local Warlord contributes having his men dig fighting holes to avoid the area attack, and that the creature can't jam its head in and eat anyone. And a request to the giant tagging along with them out of an honor debt to build a huge spiky wooden cross and try and jam it in the things mouth.
Shit goes off like a dream. The creature fails a perception roll to not mistake the heat packs for people, wastes its breath weapon. Then the giant charges, it lunges at her, and she counter-hits the cross into its gaping maw and retreats away.
The creature panics and flails, unable to dislodge the foreign object, and while its riders stay on, they lose control of it, and after being hit several times, stabbed from below as it rolls over the foxholes, and unable to retaliate, it begins to flee.
The two most acrobatic combatants in the party board it as it turns past, and run up its length killing the distracted riders in methodical fashion, or just throwing them off into the snow for someone else to finish.
Could have been a hard fight, but the genuine plan brought to the table made short work of it. Easily one of the most memorable fights to date, and not a bit of it reliant on 'class roles' or 'special abilities' being employed to maximize Red Number Generation.