Deck Idea
Interrogator's draw one or pay 3 life it the ability payoff for small minions that can not be blocker, due to stealth. This deck should make the enemy wish they had played Scent Hounds and Watch Tower.
Every minion has either stealth, grants stealth, or profits from being stealthy, so it can hit the Avatar, or be near it (Men of Leng, Court Jester).
Fade replaces itself and gives your minions stealth again, so they can keep hitting the enemy Avatar unblocked.
Grapple Shot is just the best Air spell and should always be in the deck. It also procs your Interrogator twice.
Vanishment is great, when you have more than one minion out, and also replaces itself naturally.
Bligthstone slows the enemy by denying threshold and mana, and might disable utility sites. The enemy won't be able to remove it, when a Sly Fox is hidding this thing on their site.
Algae and Twilight Bloom, as well as Lighthouse, just make your mana base consistent.
Floodplains and Undertow enable moving enemy minions. Towers for that pipedream Sly Fox into Grapple Shot turn two play, Rivers for consistency/draws, Phyxis for disabling problematic stites, Perilous Bridge to defent your own Avatar.
Zap! - Just ends the game on DD
Disenchant - Removes a artifact or aura central to an enemy's plan
Sleep - Removes a large and dangerous enemy minion
Teleport - Escape for your Avatar, or needed mobility to reach the enemy
Whirlwind, Windblast - Forced movement shenanigangs, Wildcards
Drown, Monstermorphosis - Sidegrade variants on Sleep, to handle huge and dangerous minions, or artefacts
Raise Millitia - If you are late into the game, and a swarm of Skeletons might do the trick, or they are needed as blockers.