Harvest Wurm is a land recursion card that requires you to return a land or else you have to bury (sacrifice) this summon (creature)
Summon: Primal Garuda gives a little bit of spot removal along with 2 turns of flying for Steiner
Many cards were designed purely with flavor in mind and are overtly unbalanced when compared to todays design standards
Combine this with some card draw and search options, and you've got the beginnings of something beautiful - but only the beginnings
And that's the goal of Dimir Thieves: use cards like Siphon Insight, Gonti, Lord of Luxury, Thief of Sanity, Xanathar, Guild Kingpin, and more to steal our opponent's expensive cards and (hopefully) use them to beat our opponent
Remember when I said that holding back development for counterspells was generally a bad idea in limited