This is easy but will take significant time. All you have to do is to collect at least 5 of the Daredevil action figures you see lying around. There are more than 5 in all and any you collect past the ones you need will count as XP. It takes a while only because there are so few figures and they are spread over all of the acts.
You need to collect 5 of the Daredevil figures to unlock this achievement and it also unlocks Daredevil as a playable hero. The locations are:
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ACT 1
WRENCHWORKS
OMEGA 1
Down right set of stairs in 1st conveyor room.
ATLANTEAN TRENCHES
ATLANTIS 2
Inside the safe near the sub(After you get the combination from the trapped Atlantean).
MANDARIN 2
Beneath 2nd fire breathing dragon statue on the lower level.
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ACT 2
Dr Strange's Base
Up the left stairs upon entering the room at the end of the balcony.
MURDERWORLD 1
Small room closest to the entrance to the path of the spiked wall.
MEPHISTO 2
Where the 2 fire giants spawn( Near the "L" shaped area of the map by a dry tree)
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ACT 3
BIFROST 1
Solve the puzzle near Odin's left hand.
ASGARD 1
Small forest clearing by the wide, straight bridge to the left.
NIFFLEHEIM 1
Jump on top of the building near the ramp(Near the Fire pit where you get your key)
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ACT 4
SHIAR 3
Northwest above a "zigzag" section on your mini-map in an uncharted area.
SKRULL 4
Inside the right cell you open with the co-op switch.
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ACT 5
Near the beginning of Castle Doom is a raised walkway heading in 3 directions (just before the door to the Hall of Many Doors). Destroy the two statues to reveal two chests. One will has a Daredevil action figure.