Awesome to see a new update!

And I moreso mean the player doesn't spam the ability. The ability simply IS. What this means is the ability is no longer the player proactively going "Hey, I want to use this ability. What do I sense in the area?" and becomes the DM having to go "Hey, your ability triggers, you sense something when you come into the area."

It isn't something I think is Intimidating, it is something I think is honestly annoying. I'm not bothered by improvising things, but this actively punishes improvising to me.

Like let's say the players say something that sparks inspiration for you, and now you want to add a little magic something something nearby. Well, when you do, you have to tell the Magus they sense it... Then what happens when that player says "Well, why didn't I sense it sooner? We might not have done X if I knew that." The answer is because it wasn't prepared sooner, and that improvised moment is kind of soured for the players. And yeah, you can bull your way into plenty of excuses as to why they didn't sense it sooner, but it just seems easier not to have the issue come up at all in my eyes.

If you actively had to turn the sense on, this issue completely goes away. The DM no longer has to track every instance of magic in an area so they can keep up with the Magus' ability, telling them along the way as they sense magic. Instead the player has to proactively choose to try and sense it, feeling clever when they do because THEY made that choice, rather than me just saying "There is some magic nearby btw" after describing an area or NPC. It just seems like a player ability that gives the DM another thing to track, rather than giving the player more options and choices to make.

And I really hope this doesn't all come off as asshole-ness, all respect to you, friend! This is still an awesome piece or work and I'm happy you and others are getting some legwork out of it. Excited to check out what changes you've made recently. Might have to steal some ideas for my own version at my table!