Legacy Death's Shadow deck
Death's Shadow is a strategy that became popular firstly in Modern and its strength and popularity allowed it to seep into Legacy. The strategy focuses on self-life-loss to maximize Death's Shadow power.
Overview
Death's Shadow is a highly resorceful deck with tools to deal with most threats.
The deck has access to discard, counterspells, card selection and cheap removal.
Since the deck draws a lot of its power from making the player lose life, the usage of Reserved List old dual lands (and any Reserved List card) is completely optional since shocklands are already very present in the deck's game-plan.
Some players may even describe this strategy as "Modern's Death's Shadow, but on steroids".
The variety of disruption available in Black (Inquisition of Kozilek, Thoughtseize, Hymn to Tourach, Unmask) is also key in allowing for this variety of color-choices. It can be found in: Mono-Black, Black-Red, Black-Blue and Grixis.
Mono-Black
The one which depends on the Reserved List the less. It focuses on Black cards, but may do minor splashes for cards like Apostle's Blessing, Noxious Revival, Mutagenic Growth and Gut Shot.
It decreases its own life with Snuff Out, Thought Seize, Infernal Grasp, Dismember, Street Wraith, Agadeem's Awakening and ocasional fetch lands/shocklands exclusively for the life-loss. It can add Reanimation with Unearth
Black-Red
The deck gains access to Lightning Bolt, Temur Battle Rage, Claim/Fame, Faithless Looting, etc.
It may also benefit from Dragon's Rage Channeler, Kroxa, Titan of Death's Hunger, Young Pyromancer (which may also lead to the inclusion of Cabal Therapy, Bomat Courier, Bedlam Reveler, Seasoned Pyromancer, etc.
It may also try Blood Moon
Black-Blue
The deck gains access to Daze, Brainstorm, Force of Will, etc.
The Blue splash is perhaps the most popular for the card-draw and the free counterspells. As an Example: Dress Down, Stubborn Denial.
It also has some popular creatures: Murktide Regent, Brazen Borrower, Delver of Secrets.
Grixis
It is likely the one with the most complete arsenal available.
An example of the Grixis list can be found below.