Newer Player / GM question on Basic Rules on "against DC" checks

[Anunaki]

So finally trying to get games going. Have what I know should be a basic question but I am failing to find an example to explain it. When it is saying "Can make a check vs. creatures x DC", what is actually happening with the dice to determine that check? Specific example. If Goblin Dog has Will +5, and you want to attempt Command an Animal. It says attempt a nature check vs creatures Will DC. PC has +2 Nature profeciency. Who rolls what? I can't seem to find any example of this. Does this mean the GM rolls a D20 and adds 5, and the player rolls a D20 and adds 2, and if PC is higher, PC wins the check? Or does this mean only the player rolls a D20 and has to beat a 5? Or is it a 10 and add 5 to it so player needs to roll a 15? Kind of confused here on something that I know is a basic concept of the system.

[HammerJack]

The PC makes a Nature Check. That means they roll 1d20 and add their nature modifier (WIS mod+proficiency+any other bonuses). So a level 1 PC with 10 WIS and Trained Nature would be rolling 1d20+3 (0 WIS mod+3 proficiency).

The Goblin Dog has a Will Modifier of +5. That means it's Will DC is 15. A creature's DC for something is its modifier+10. The Goblin Dog will not be rolling dice here.

So if the PC's roll is 15 or higher, they succeed. 25 or higher, they critically succeed. 5 or less, they critically fail.

Side note: The PC having a proficiency of 2 sounds like something you should take a second look at. Trained proficiency is 2+level, so a proficiency of 2 is only likely with some abilities that allow you to add some smaller2 amount as a proficiency bonus in skills you are Untrained in.

[Mathmuse]

Pathfinder 2nd Edition uses a single d20 roll, 1d20+bonus. The other side has a passive DC, 10+bonus.

In Anunaki's Command An Animal example, the Will DC of a Goblin Dog with Will +5 is 10+5 = 15. If a 1st-level dog handler has trained proficiency in Nature and Wisdom +1, his bonus to Nature rules is +2 from trained, +1 from level, and +1 from Wisdom, for a total of +4 to the Nature check. The player of the handler rules 1d20+4, which means rolling a 20-sided dice and adding the bonus +4 to the rolled number. If the result is 15 or more, that means he successfully commanded the goblin dog. If the result is less than 15, that means he failed to command the dog.

A result of 25 or more, 10 more than the DC 15, would be a critical success, which sometimes gives extra effects. A result of 5 or less, 10 less than the DC 15, would be a critical failure, which sometimes gives an extra penalty beyond failure.

Pathfinder 1st Edition has opposed rolls were both sides of the conflict roll. That creates a spread of options from -19 to +19. I remember once when a highly skilled rogue trying to sneak past a rune giant guard rolled at natural 1 against a natural 20, the only result that would let the guard notice him (nat 1s and 20s are not automatic failures and successes in PF1 skill checks). In addition, a +1 bonus means something different when the probability distribution is a triangle rather than uniform, and that throws off the math that balances an encounter. Therefore, Pathfinder 2nd Edition always uses a single roll to determine success versus failure.

[breithauptclan]

If you are familiar with previous versions and the take-10 rules, this is where it went. Not the Assurance feat.

A DC is calculated from a bonus by adding 10 to the bonus value.