So somebody is testing out the new DnD 5, and, well...
Why are level 20 characters in D&D Next/5e so blisteringly incompetent, /tg/?
This is how skills work in Next/5e. You pick out 4 skills (out of a list of 26 skills; hooray for unskilled and incompetent characters, a hilarious step back from 4e's scaling skills and skill training!). You get skill dice for those skills:
>Whenever you make an ability check related to one or more of your skills, roll your skill die once and add the number rolled to the check’s result.
>Your skill die starts as a d6. When you reach 7th, 12th, and 17th level, you can either choose a new skill or improve your skill die from a d6 to a d8, a d8 to a d10, or a d10 to a d12. In short, you decide whether you want to broaden your character’s expertise or become even better at the skills you already have.
So, let us take a level 20 human ranger in Next/5e. The highest you can ever get in an ability score in Next is 20, for a +5 modifier. Let us say our ranger has Strength 20 and Wisdom 20, amongst other scores. The ranger has opted to increase their skill die every time, for a skill die of +1d12 for a grand total of 4 skills (out of 26, the incompetent twerp). Let us say his four skills are Break an Object, Climb, Listen, and Track
A character in Next/5e only ever has four feats. Let us give our ranger Skill Focus (Break an Object), Skill Supremacy (Break an Object), Skill Focus (Climb), and Skill Supremacy (Climb). This way, the ranger rolls twice and takes the higher result on ALL Strength checks made to break an object or climb, and on either of those rolls, any d20 roll of 1 through 9 instead becomes a 10.
>Formidable (DC 30): Break chains or manacles
>Formidable (DC 30): Break open a heavy door held by a metal bar or a masterwork lock
>Formidable (DC 30): Climb an oiled rope
Whoops. Even though our ranger is the greatest object-breaker and climber in the world, 72.25% of the time, they completely fail the above tasks. How did it all go so wrong?
The rest are rolls and stats and such, which I will not bother with here.
Edit: Also, apparently, Asmodeus (the devil), literally CANNOT break out of Iron chains if you wrap them around it, and with the new skill system a level 1 dirt farmer has a 1 in 4 chance of lying, convincing, bluffing, the literal devil. A level 17 with Unflappable (no roll penalties for bad or unlikely ideas, such as sweet talking the devil) paladin with has a 54% chance of convincing the devil to live a humble life as a nun.