Connected Twins (5e Race Variant)
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Your birth was destined by the gods, as the one to change this world. However, unwritten, was that there would be two of you, born mere seconds apart.
Four Eyes, More Ears. This world is not meant for you alone, your body not as strong as it could be. You may have grown accustomed to working in tandem with your twin, but that does not mean others do not find your relationship strange, nor does it mean you are twice as smart. It does however, allow you a second glance at things most would only see once. You have advantage on all Perception checks (Involving the use of Sight, or Hearing) while your twin is with you.
A Covered Back. Being together all your life, death knocks often, and you both are very skilled at keeping that door shut. When a blade swings down at your twin, you are quick to attempt to block it, and vice versa. You can use your reaction to add +2 to your AC when being attacked. At character levels 5, 11, 18, increase this bonus likewise, 4, 6, 8.
A Twinned Assault. Tapping into your promised power, you can plan a strategic maneuver with your twin. Breaking the normal tides of battle, your gift for combat shines in these desperate moments. You must sacrifice your entire round, using no Action, movement, bonus action, Free Action, or Item Interaction. During your next turn in combat, you may take two turns of combat at once. Allowing a full Two Turns in one. Using this more than once per long rest, deals 2d12 psychic damage, + 4d12 per use. This damage cannot be mitigated, nor can it be resisted. If the user is immune to Psychic damage, they take half damage instead. If used more than three times, the user gains 2 levels of exhaustion +1 level of exhaustion per use after.
Alone, but not Lonely. If an attack would be instantly lethal, killing you outright with no Death Saves allowed, your twin will take the blow for you. Dying instantly, and causing you to survive. You take the following penalties, and lose all class features and abilities, instead using the Human abilities and racial bonuses Or Variant Human.)
Simple Vengeance. The foe that killed your twin is now added to your favored enemy type.