Getting the crunch against a player with a big hand will feel especially nice
As of writing, Korean Thoughtseizes are going for just about $10 more than an English one
Getting to dig for more permanents when it dies or getting to buff the team is an excellent tradeoff for losing a 5/4 with flying and vigilance
Mechtitan Core Yes, its a little clunky, requires jumping through a lot of hoops to activate, can often be seen coming from miles away and results in the mother of all blow outs if your opponent has any kind of Stifle effect
It is always Tier 1 in the hands of an experienced player but never too dominant to become problematic
Each Background synergises better with a specific legendary creature than others, such as Scion of Halasters ability to put cards into your graveyard working perfectly with Viconia, Drow Apostate and her requirement of having four or more creatures in your graveyard