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.

Minions

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).

Magics

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.

Artifacts

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.

Sites

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.

Collection

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.

Gothic Petty Thieves W/A

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