Base Class: Barbarian
etc.
Staggering Blows
You may now make an opportunity attack against a creature that has become Prone or Wallsplatted within 15ft of you, this movement is free.
When attacking a creature, no more than one size larger than you with a weapon that has the Heavy property, and while raging, you gain the following benefits.
On a successful attack against a creature, it will receive the special Staggered condition.
A Staggered Creature will immediately be rendered prone upon receiving any amount of displacement from any source.
EX. A creature that is Staggered is shoved five feet. It will immediately fall prone after being moved.
Alternatively, displacing a creature into a solid surface or other creature of equal or greater size, with a minimum of 5ft of movement remaining, will cause the Wallsplatted condition.
The Wallsplatted condition functions the same as the prone condition, only with the creature remaining upright.
Upon receiving either, the Wallsplatted or Prone condition, the creature will be cleansed of the Staggered Condition and become immune to it until it recovers.
A creature cannot receive the Staggered Condition and be knocked prone in the same instance of damage, But they can do so in the same turn.
You may now shove as a bonus action.
Rune Carver
When making a successful attack against a creature that is Prone Or Wallsplatted while raging, you gain a rune.
Runes are lost upon ending your turn without making an attack against a Prone or Wallsplatted Creature.
You can have up to 5 Runes active at one time.
A higher number of Runes grants escalating benefits as follows-
1 All displacement you cause is increased by 5ft
2 Your movement speed increases by 10ft
3 All damage you receive is decreased by your Rage Damage Bonus number
4 All displacement you cause is increased by an additional 5ft
5 Your first attack on each of your turns adds your Rage Damage Bonus twice
Rune Rage
Your Rune Carver subclass feature can now support 10 Runes at a time.
6 You gain 2 additional points toward your armor class
7 Your strength score increases by 2
8 A shove can be made as a part of the Attack action once on each of your turns.
9 Your attacks against Prone or Wallsplatted creatures ignore resistance to bludgeoning, piercing, and slashing.
10 On your subsequent turn, you enter Rune Rage.
Rune Rage Will...
make all of your attacks Critical Hits for one turn.
Give you Invulnerability to non-magical damage for one turn.
Deal (nonlethal) psychic damage equal to all of your hit dice at the start of your next turn.
Cleanse all runes from you at the start of your next turn.
All creatures in combat with you immediately become aware of you the turn before you enter Rune Rage
...and they also become aware of exactly what it is
Rune Wrath
You will now only lose 5 runes upon not making an attack against a Prone or Wallsplatted creature.
Additionally, your Rune Rage Can be extended for one turn if you reduce a creature to zero hit points with each of your available attacks on that turn.