"Eyes on me."
The best defense is a good offense. Champions of the Aegis best exemplifies this philosophy of war, protecting their allies by being the most threatening person in the room. Ignore them at your own peril.
Level 3
Armor Master.
You are proficient with plate armor.
Retaliating Strike.
After you Interpose, you can make a free melee attack that ignores disadvantage, dealing STR+INT bonus damage.
Level 7
Pay Attention.
When you use Coordinated Strike, your target enemy is slowed when moving towards your target ally and is taunted towards you. The enemy may make a WIL Save (DC 10+INT) at the end of their turns, ending both effects on a successful save.
Sentinel.
Your Interpose can now target empty squares in Range 2 and can be triggered if an enemy enters a space in it, entering the enemy's space and moving them to an adjacent space before slowing them.
Level 11
Stand Your Ground.
You have Aura 1. This is difficult terrain for enemies, and allies have full cover against projectiles passing through your aura. You may also Slow yourself at the start of your turn to increase this to Aura 2 and render yourself immune to forced movement until the start of your next turn.
Level 15
Rampart.
Enemies that start their turn in your Aura cannot teleport, fly, burrow, or start any sort of special movement while inside the Aura. Allies in your aura have advantage on STR and DEX saves.