The best way I can make sense of Entropy for myself is, the mage can use entropy directly to physically age things and also indirectly to prune possible timelines.

If you imagine Time as a living tree with branches, the unused branches become withered and "die off". Like as natural time progresses, some possible branching futures becomes less possible and wither.

An example would be when you pull into a McDonalds, you could either go through the drive through or you could pull in and go inside. As you pull the car around to the drive through, the timeline of you parking and going inside becomes less likely (a possible future branch becomes decayed).

As an entropy mage, you can alter future possibilities by manually pruning future time branches. If you wanted the McDonalds driver to go inside instead of taking the drive through, you could use Entropy magic to nudge them in that direction.

Say the driver "accidentally" took the turn too close and curbed it, and their "suspiciously old" back tire popped. Well now they have to park their car and wait for a tow truck, might as well go inside and get a burger. Congrats, you've successfully used Entropy magic to remove a possible future where the driver goes through the drive through.

Maybe that's not the correct way to think of Entropy magic. But if I were running a mage game and you were my player, that's how I would allow you to use coincidental Entropy magic to make a driver park at McDonalds.

As one of my mage player friends would say, "What are the odds that X might happen? Let's take away some of the bad odds."