Spellslinger decks dont run many creatures, but tossing away a stray Goblin Electromancer or something is feasible in the late game, especially if your Flare of Duplications resolution gives you a win
While Ancient Gear Factory provides a unique way to summon Level 5 or higher monsters without tributing, there may be better options like Ancient Gear Catapult which can special summon an Ancient Gear monster from the deck by destroying a spell/trap card, offering more versatility and speed in the deck's strategy
One of the best ones for when you need to sacrifice a land is The Gitrog Monster
Chart shows the price of Dwarven Sol Ring [Serialized] #409 at the end of each month going back as long as we have tracked the item.
The philosophy is that every card that exists in the Modern format is, unsurprisingly, a part of Magic's modern game design
Honorable Mentions Nonsensical Commanders Theres a huge category of cards that are commanders that dont actually make sense to put in the command zone