YAL's PF2e roll result visualizer

Aid allows you to spend an action and a reaction to give an ally a circumstance bonus to a skill check or an attack roll.

So, for example, you might say that you'd like to pretend to take a swing at an enemy to give your ally a better chance of hitting them. Your check is rolled outside your turn so MAP doesn't apply to it.

The typical DC is 15 (not level-based!) so this gets easier to pass as your level increases; with Assurance, you can automatically succeed the check as early as level 3 and automatically critically succeed it at higher levels.

Most adversaries wouldn't fall for the same trick multiple times so your GM might increase the DC when aiding with checks against the same creature, but still you can help your allies get an extra critical hit or two.

Suppose you have a level 4 Fighter that's an Expert in Athletics.

Your Assurance roll to Trip would be 18 (10 + 8 prof) while your roll bonus would be +12 (4 str + 8 prof).

Doesn't sound like a good deal, right? You'd have a 75% chance of rolling the same or better as Assurance result.

However, if you are doing your Trip as a second action with MAP, your bonus would be +8, which is 55% chance to roll same as better.

And on a Trip after two attacks, your bonus would be +4, which is mere 35% chance to roll same or better.

In other words, it's not a bad bet to try an Athletics manuever with Assurance on an enemy as your third action, and if that works, you can do that every turn.

Assurance works even better if your character isn't Strength-based - so you might have a gnome Magus with 4 dexterity and -1 strength and still trip/shove weaker foes just fine.

pf2e's 3-action turn structure means that finding ways to waste a large enemies' actions is a pretty big deal, which includes moving away if you're the only character next to it and it will have to move after you.

Bonus points if you have a reach weapon and Reactive Strike while the enemy doesn't - then you can Stride two tiles away and have the enemy choose between spending two actions on Step or taking a MAP-less RS hit from you.

A little defense can be nice to have too, especially if there's a possibility that multiple enemies will be attacking you.

If you have relevant Additional Lore or are still at low enough level that you are only 3 points (1 attr + trained vs 4 attr + trained) behind someone specialized, you can always try your lock at figuring out what exactly is it that you're fighting.

And who knows, maybe this peculiar beast has unusually low Reflex or a deeply concerning special ability that it hasn't used yet.