Baron Opal II
Legend
Because they are using their abilities together, thinking outside the box! The fighter will get killed just fighting it, regardless how much he is healed by the cleric. The demon is partially immune to the magic of the wizard. There was cleverness and inventiveness in surmounting the problem. Just attacking it, lightning bolt-ing it, whatever isn't enough. It wasn't a thief picking a lock or a cleric turning undead. The party had to either:Hang on though.
The cleric cast a spell - ability inherent to the character class. The wizard casts a spell - an ability inherent to the character class. The fighter gives up a magic sword - the only thing in this story that isn't inherent to the class. Fighter goes full defense (takes the Dodge action) - straight up rules from the character sheet and nothing particularly creative here.
How is this not looking at character sheet as a set of keys? Because the players looked at each other's character sheets and came up with a plan together? It's creative, sure, but, it's still 100% looking at character sheets to solve the problem. It's not like they did anything that required anything other than direct spell descriptions.
IOW, this example could have been done in any edition and uses nothing but the mechanics of that edition. That's generally not what people mean when they say that the players are being creative. Now, to me, I love it and I would absolutely reward the group for doing this. It's a fantastic solution to a problem and I love it when players actually work together to solve something. It's why I adored the Warlord class which rewards this sort of play directly all the time. But, this isn't really what is generally meant when people talk about how this or that edition forces creativity.
1- Run Faster
2- Kill It In One Shot
And they were able to do the latter.
And, yes, I should hope you would be able to do this in any edition. I'm not saying otherwise. I was giving an "A Game" example.
(FWIW, this was done in AD&D back in the day. I don't see why it couldn't happen in any other edition.)