When you attack, you can pull off a counter to do one of two things - Lightning Blast anything for 4 damage (Red) or give Guile lifelink (White) and indestructible (also...White) for the turn
In the original games, it is a revive item, restoring a fallen ally, but with minimal health
2020-11-10 Although the ninjutsu ability has the creature enter the battlefield attacking, it was never declared as an attacking creature (for the purposes of abilities that trigger whenever a creature attacks, for example)
Hangarback Walker is high on my list of cards to support sacrifice decks and delirium, and while it has the potential to be significantly more powerful than Solemn Simulacrum I believe it firmly lands in the category of colorless cards that feel like youre paying for what you get
At the time of writing, her Enchanted card is listed with a value of $774.90 USD on TCGPlayer