American game, American rules. Besides, what was the last great song or piece of fiction that was entitled with a unit of the metric system - other than weight because that usually refers to elicit substances? The Who's "I Can See For Kilometers and Kilometers"? Ray Bradbury's classic...
Do you know that fire should be used to stop a troll from regenerating and kill it irrevocably? You do? And yet you don't even have trolls living in your world. What gives you the gall to think that intelligent races that have been dealing with trolls and other supernatural-types for the...
There needs to be more input beyond simply opposing spell level when rolling. The Arcana skill differential between the caster vs the counterspeller would be a start. Then add in another input if the target has magic resistance.
Nine times out of ten, the answer is Magic. It's the prime motivator of all existence in canonical D&D worlds. Trying to reconcile it with science is an impossible task.
I ruled recently that NonDetection could not be used to keep someone with See Invisible (a divination spell) from seeing an invisible creature because they weren't targetted by the spell. It gets much trickier when you get to Mind Blank which makes you IMMUNE to divination spells, not 'can not...
I wasn't into gardening 20 years ago and I'm not into gardening today. My skill bonus hasn't changed for that skill. Not true for my core proficiencies, however.
Back in the day there was a tendency to check EVERYTHING. Was that smoked turkey hanging in the larder stuffed with a key to the desk in the groomsman's room? Check every section of wall for secret doors. Develop extreme myopia by peering through the Gem of True Seeing near constantly. Run...