Agnes; Pythoness

Backline, Ranged 

Driven to insanity by her undeath, Agnes takes grim satisfaction in watching her enemies suffer as she has.

For the cold and calculating, particularly at long-range sniping.

Innate: Living Memory [Passive]

Agnes retains vision of anywhere she has seen for 8-20 seconds.

Arc Arrow

Launches an arrow toward the target point. The arrow will travel along a parabola, arcing based on how much she must turn to launch it. No turning means a straight line arrow; a 180° turn forms a large arc. The damage increases dramatically based on distance travelled and heavily arcing arrows.

Aligerous

Agnes stands still, and fires up to 2-5 arrows which travel in a straight line, damaging the first enemy they hit, as an 'attack'. The arrows have long range, and each subsequent arrow travels a bit further. Damage increases with distance travelled.

Blindsided [Passive]

An aura which grants 20% bonus damage to allies if they are in enemy fog of war, or otherwise invisible to their victim.

Ultimate: Bleak

Releases an evil spirit in a line. Enemies touched by this spirit will lose allied vision, sight range, and 1 armour per second for the duration of the ability.

Notes:

• A pure 'sniper' hero.
• Arc Arrow is probably the most difficult skillshot in the game, requiring a great deal of practice and intuition for how the arrow arcs. An experienced user can land precision arrows against enemies off-screen, or even when they're trying to hide behind other units.
• Arc Arrow is the only skill in the game to have two kill songs: the second playing if she scores another kill with it shortly after it comes off cooldown.
• Aligerous makes for good follow-up damage; a full barrage can be very painful late-game. 
• Pyth is 'mained' more than any other hero, due to the unique challenge of playing her successfully.
• She lacks any good tools for escaping or protecting herself; relying on keeping her distance and staying out of sight. For this reason, Assassin is a dangerous opponent for her, since she can sneak up undetected.
• She usually builds either attack damage items, or mobility/kiting ones.
• After a long reign of terror, Arc Arrow was nerfed to deal at most 60% of a target's maximum life, rather than having fixed damage which was often high enough to instantly kill squishy heroes.