Its possible Hive Stirrings isnt worth it and should be some kind of actual Sliver creature so you can get colored mana to cast it from Sliver Hive, but being able to make multiple Slivers with a single card seems pretty powerful when you have so many ways to pump them
Bruvac the Grandiloquent Tetsuko Umezawa, Fugitive Unesh, Criosphinx Sovereign Arcum Dagsson Lady Octopus, Inspired Inventor Talrand, Sky Summoner Baral, Chief of Compliance Azami, Lady of Scrolls Eluge, the Shoreless Sea Urza, Lord High Artificer These are the Mono-Blue Commanders that give you a reason to sleeve up a pile of Islands beyond the simple joy of saying "no" to your friends over and over again
Cards printed in the EU look different to cards printed in the US
Its not enough to slap a 17+ label on the box and be done with it
The big weakness is hitting those creatures
Finale of Devastation (by itself) is currently selling at its cheapest for over $49.99 (it's sitting around $51 on TCGPlayer), and that's more than the retail price for the seven cards listed