Two main ideas: give players something to look forwards to at 3rd level while also giving more definition between characters. At 3rd level, your character has been with you for a little while. They’ve been through a few things. They’re ready to grow.
I like the idea of 3rd level perks tying into the first level ones, but without any character building restrictions other than your concept. If you want your mage to learn weapon mastery, I won’t stop you.
So first we have Weapon Mastery, which again increases weapon damage dice by one step, and increases critical strike range. This is just the Fighter perk again, but this time anybody can take it. If the fighter takes it, they’re either wielding a one-handed weapon that deals 1d10 damage or a two-handed weapon that deals 2d8, which is pretty fearsome.
Guardian is something new- it adds the ability to protect others. When you’re standing next to an ally, you can take their damage. It also gives you 1 DR and +1 defense, so you can better endure whatever you have to endure.
Berserker is also new. When you take damage, you gain that much Rage. For every 3 points of Rage, you add +1 to your attack and damage rolls. For every 6 points of rage, you gain +1 Damage Reduction. And Rage, of course, dissipates once the threat has passed. This works best if you have a lot of hit points, and if you want to fight.
Energy– gain 2 focus and when you spend a point of focus, you can gain +1 to attack rolls and Defense until the end of your next turn. Not terribly useful unless you’re a martial artist, but helps you land important strikes and encourages you to chain your unarmed striking (since the bonus carries over).
Hands Without Shadow lets you regain focus when you land an unarmed strike. Also, you get to roll your unarmed damage twice, taking the higher result.
Peace and Calm lets you dart around when you spend focus. It should probably also give you more focus. I haven’t decided on this one yet.
The Assassin has two easily movable parts- they need their enemy to remain unaware of them, and they want to deal damage.
Dangerous lets you automatically apply hit and also the critical effect of your weapon to an enemy if you are the one to engage. Imagine a bold assassin walking up to his target and jamming a dagger deep into their guts.
Sharp Eyes gives you additional 1d6 damage if you strike an enemy against whom you have advantage.
Dirty Fighting lets you (or an ally) get advantage on your next attack if you succeed by at least 5 on your attack roll.
Adepts like to cast spells but don’t really have a way to gain more, so here are a couple things to help them out:
Innate Sorcery: If you already know a 1st level spell, you learn one 2nd level spell and two 1st level spells. If you do not know a 1st level spell, you gain two 1st level spells and spell points equal to your level.
Arcane Knack: You learn a 1st level spell. You gain 2 spell points. Whenever you cast a spell of 1st level or greater, if you succeed, you regain that many spell points.
Acrobats like to move and dart around, and they also get a lot of mileage out of their abilities outside of combat, so let’s do something like this:
Tumble: Whenever you spend a point of focus, you may move up to half of your speed in any direction. You ignore difficult terrain or an non-blocking obstacles in your way.
I guess Acrobats get the short end of the stick for now. I’ll think of something else later.
Now for the Mage-centric perks:
Runic Inscription: When you take a long rest, you may inscribe your weapons and armor with runes. You have 2 less spell points as long as you are equipped with runic weapons and armor. You gain a +2 bonus to defense as long as you are equipped with runic armor. You may add your proficiency bonus to your attack and damage rolls as long as you are equipped with runic weapons. You may release the runes’ power during a short rest, if you wish. The runic weapons and armor only function in your hands.
Battlemage: Whenever you strike an enemy, you may immediately cast a spell of your choice on that same enemy, or on yourself. That spell costs 1 less to cast.
Practiced: Select a single skill. Whenever you add your proficiency bonus to a roll related to that skill, add your proficiency bonus +2 instead.
Hyperliterate: Add your proficiency bonus to checks to transcribe spells into your spellbook. Your spellbook can contain 5 additional levels of spells.
Tome of Power: When you cast a spell that is written in your spellbook, you may spend 1 point less to cast that spell.
Living Codex: Your spellbook hovers around you when not in use. When you are not casting a spell from your spellbook, it provides you with +2 defense.
That’ll do for now, I think.
For my next brainstorming lesson, I’ll try and come up with some compelling options for the level 6 ‘Capstone’ perks.