Japanese trophy cards (awarded in tournaments in Japan) and older promo cards frequently show steady appreciation over time due to very low supply and high status among collectors
And its ridiculously cheap
Its basically the creature version of Sneak Attack in the sense that youre cheating time, not mana, and the extra text about warping artifacts and red creatures helps you to keep deploying threats so the attacks never stop
Clarion Conqueror is an absolute menace and can help its controller run away with the game
And what a massive member of the crew this will be
It begins at the point in the game where youre at six lands or so and can go End of turn cast my Spectral Sailor, draw a card, use my Dive Down to protect it from your removal spell, and force you to have a second answer or the game ends. Ive had some games go very long in matchups like that, though, and a Spectral Sailor in hand with nine lands on the battlefield represents a guaranteed three-for-one