They resolve even if the Adventure spell is countered before the copy is created
Another unique error from early WOTC Pokemon is the Hitmonlee "Stain Error" from 1st Edition Fossil
Drivnod, Carnage Dominus fits well in aristocrat decks with the extra dying trigger
Compare with Chromatic Lantern from Return to Ravnica (3 drop, Lands you control have "Tap: Add one mana of any color to your mana pool." Tap: Add one mana of any color to your mana pool.) This is a solid rare
Creature flips are both the most broadly accessible, and restrictive in terms of deckbuilding, of this general gameplan while there are an absolute plethora of great options, and you nearly always have access to something available for Polymorph targeting, cutting down on creatures is a tough call, and oftentimes you'll need to truly lean into some other gameplan, as is the case with Urza in artifact-based stax, or spellslinging control