Double tapping a direction makes Isaac quickly dash in that direction.
Isaac is immune to damage from all sources during the dash, with the exception of Blood Donation Machines, Devil Beggars, and similar self-damage active items.
The dash deals damage equal to 4× Isaac's damage + 8.
The direction of the dash can be angled by holding another button.
The dash has an approximate 3 second cooldown.
Isaac will stand in place for a quick moment before dashing. During this time, the dash can be cancelled if Isaac moves in the opposite direction, or angled if a direction perpendicular to the charge is inputted.
Isaac gains a shield for half a second during the end of the dash. Unlike the initial dash, this shield will make Isaac immune to damage from Blood Donation Machines and Devil Beggars.
If Isaac collides with a wall or obstacle, he will recoil a short distance back and also push away all enemies near the impact. Enemies pushed into walls or obstacles take 10 + 2 * (floor - 1) damage.
With a controller, tapping the joystick is rather inconsistent, and the dash can often activate by accident. Using the directional pad instead is recommended.
When Mars's dash is charged, Isaac will occasionally flash brightly, and visible steam will emit from his nose.
Extra care needs to be taken with this item, as tapping for precise movements too quickly will cause a dash.
Mars' quality is treated as 1 for the purposes of Bag of Crafting.
Synergies
Camo Undies: Can be used to deal damage without breaking the confusion effect.
Kamikaze!: Kamikaze can be used without taking damage while dashing.
A Pony / White Pony: Lowers the dash cooldown to approximately 1.5 seconds.
Tainted Forgotten: Tainted Forgotten will charge on double-tap if Tainted Soul is not holding him. This can be used to let Tainted Forgotten attack enemies from a resting position, or move him away from damaging hazards so Tainted Soul can pick him up.
Blood Donation Machines, 
Devil Beggars, and similar self-damage active items.
Isaac will stand in place for a quick moment before dashing. During this time, the dash can be cancelled if Isaac moves in the opposite direction, or angled if a direction perpendicular to the charge is inputted.
Curse Rooms and open 
Spiked Chests/ 
Mimic Chests without taking damage.
Shopkeepers.
Bag of Crafting.
Camo Undies: Can be used to deal damage without breaking the confusion effect.
Kamikaze!: Kamikaze can be used without taking damage while dashing.
A Pony / 
White Pony: Lowers the dash cooldown to approximately 1.5 seconds.
Tainted Forgotten: Tainted Forgotten will charge on double-tap if Tainted Soul is not holding him. This can be used to let Tainted Forgotten attack enemies from a resting position, or move him away from damaging hazards so Tainted Soul can pick him up.
War when holding the item, referencing the Roman god of war, Mars.
Astrological Signs 
The Binding of Isaac: Rebirth
