Eldrazi took Modern and Legacy by storm when
Oath of the Gatewatch dropped, a function of
them giving two broken lands toys for them to
play with. Thought-Knot Seer (along with Reality
Smasher) were the biggest beneficiary of this: a
4/4 that you can drop on turn 2, that lets you
take the best card from your opponent's hand so
that they'll never see it again. Who cares about
the death trigger when it's a good,
burn-resistant body that already disrupted them?
Thought-Knot Seer is potent on turn 4, but being
able to "cheat" him in on turn 2 or 3 makes him
oppressive. If you're playing a format where
there are lots of colorless-producing lands or
tricks, be ready to see this. It's an effective
clock on its own, and it can keep your
opponent's from ever starting.
It's sad that this card will probably be
remembered mostly for its role in Eldrazi
Winter. The colorless mana symbol was a fun idea
and the cards that required it for their casting
and/or activation costs were often quite unique.
This one was just designed to be extremely
powerful - by using Wastes, you basically get a
creature that's a major upgrade over Tidehollow
Sculler (they never get the exiled card back.
Especially painful in a singleton format!). He's
a lot fairer when you can't cast him on turn 2,
because Eldrazi Temple is banned or not in your
deck for some other reason, but a more powerful
discard effect than you often see nowadays plus
a creature that fights like a baloth is nothing
to complain about.