Agility is the Attribute which characterized by Actions with Wounded enemies (Finish Off, Leaflurker), creatures with Lethal (Territorial Viper, Fighters Guild Recruit or Skooma Racketeer), Pilfer (Goblin Skulk, Quin’rawl Burglar or Daring Cutpurse with Prophecy) and Last Gasp (Deshaan Avenger, House Kingsman or Varanis Courier) keywords. As for the keyword Lethal, it is not a popular keyword in ranked mode but it is strong enough. As for the Pilfer, it is speciality of cards with Agility Attribute. You can play cards with born keyword Pilfer, or you can give it to all your creatures after playing Support card Thieves’ Den.There are some Agility cards which have unique keyword Move (Dune Smuggler or Shadow Shift). They can help you to control the board and do good trades.
This Attribute is not so popular in Control decks, but you can play Agility cards there. There are some cards that give you growth of your max Magicka (Torval Crook) and it is awesome to play Ramp control decks. There are also some good cards with Prophecy and Drain (Fighters Guild Recruit or Moonlight Werebat) and it is good for Control decks.
The cards with Agility Attribute are perfect to play them in Midrange decks. You can control the board with destroying Wounded enemy creatures, you can trigger your Last Gasp and Pilfer effects after playing Necrom Mastermind. Ungolim the Listener is the perfect one-drop to play in Midrange decks because it gives you extra draw and three strong cheap creatures with Lethal.
In Aggro decks you don’t need to play cards with Agility Attribute because they are slow.
On Arena most of cards with this Attribute are very strong.
Agility Attribute is one of the components of four classes: Archer, Assassin, Monk and Scout.