Well, it flies and it can feed your Flare of Malice
Its death by a thousand cuts, but those cuts add up really fast when you produce tokens from Reverent Hoplite, Evangel of Heliod, and similar effects while doubling down on those triggers with Delney and doubling those tokens with cards like Anointed Procession
These tools can range from simple spreadsheets to more complex algorithms, all aimed at providing insights into deck composition, synergy, and competitiveness
It might not look like much at first glance, but Delver is so strong that they named an entire deck archetype after it in Magic's cheaper competitive format, Pauper
Examples of watermarks are the guild symbols in Ravnica sets, the clan symbols in Khans of Tarkir block, the Mirrodin and Phyrexian symbols in Scars of Mirrodin block, and the Planeswalker symbol on the story spotlight cards