Abomination. It's a powerful evasive threat and a delve enabler. Treasure cruise is also great, but, well.... The best sultai decks have exactly one treasure cruise, but as many as four abominations. Let's play the odds we'll see another cruise down the road.
Pretty weak pack for us. The best options are Set Adrift and Weave Fate. Set Adrift has the problem of being one of the weaker delve spells and competing with the better ones for deck slots, while Weave Fate is just a mediocre effect for the mana cost. I'm going to side with Set Adrift. It might get cut if we pick up a few of the better delve spells, but it's an effect I would rather have in the deck if we don't go too heavy on delve.
Sultai scavenger, and we cool it on delve cards for a bit. We need to start prioritizing cheaper creatures and effects, which all incidentally support delve. In fact, it may turn out in hindsight that mardu skullhunter was the correct pick here.