TFL 17.07.06

AC and You

So a lot of things have been changed since DnD 4e. Most notably is how characters scale. WotC decided to move away from the near godly bonuses of 4e and instead focus on more simulation style gaming. In my humble opinion they've made it a lot more interesting, particularly with the introduction of advantage. Rolling once and applying modifiers is cool and all but physically re rolling that failure as a success is a great feeling and holds more gravitas for the players.

Anyways without rambling too much lets look at some core mechanics.

"Should I attack the thing?" Is a common question followed of course by "how do I attack the thing?" but one thing that's particularly elusive and difficult to juggle is "what is the possibilty to hit the thing?"

Now, without making observations ("what is the enemy wearing? Is it plate or chain mail?") It will take a couple of swings before you find out where the targets AC lies. Once you have a pretty good idea you can begin to make informed decisions about your probability to hit them.

Lets look at a creature with 14 AC (a common AC in 5e). Adukal Grimviper wants to wreck this dude with his warhammer, of which he is proficient. He has to match or beat the targets AC with a d20 plus his modifiers(proficiency and strength in this case). A 13 or lower will be a failure. With his modifiers his d20 would have to pop up a 9 or lower. That means Adukal has a 45% chance of missing. "But Jerad, how did you get there?" you say. Worry not dear reader. Here is how it works. Each point represents 5% (100/d20). You then find out what you have to roll to miss by taking the targets AC, subtracting your modifiers, and then multiplying the result by 5. That gives you your probability to miss the target(ignoring special abilities). Ta-da.

Pretty useful, right? Now you can understand the importance of gaining +1 weapons or boosting your ability scores. Every +1 you gain is an additional 5% hit and fuck shit up.

You can also apply this method to saves and spell DCs to understand how effective certain abilities may be in the heat of things.

Edit: Forgot to mention that Advantage is crazy good but slightly more complex. Example below.

Example: Adukal vs 18 AC Adukal needs to roll 14 or higher to hit 13 or lower is a miss, meaning 65% chance to miss. Adukal though has Vow of Enmity of the target which grants advantage. His chance to miss is now 65% × 65% = ~42% chance to miss.

For disadvantage lets looks at Rusbpin. He has disadvatage against an enemy in half cover who has 14 AC. He needs to roll 10 or higher. 9 or lower will miss, meaning 45% chance to miss. For disadvantage we have to alter his success rate though so we convert 45% chance to miss to 55% chance to hit. 55% × 55% = ~30% chance to hit