There will be many artifact creatures in everyones Limited decks at the prerelease, so dont worry about this card not taking out two of your opponents targets
Weve already covered how well Tekuthal, Inquiry Dominus plays with proliferating stun counters, but there are tons and tons of easy and repeatable ways to proliferate each turn, effectively locking those creatures out of the game indefinitely
If you discard a nonland card, you put a +1/+1 counter on the creature that connived
2/1s for one are borderline playable even without any upside, so Kytheon, Hero of Akros doesnt have to be very good before multiple aggro decks want to run at least two or three copies
This card can be a competent card selection tool and win condition for more controlling blue Limited decks, especially UB
On top of that, it's also the card illustrated by famed Pokemon artist Mitsuhiro Arita - his first contribution to Magic: The Gathering