Commander Greven il-Vec was awesome when I was a kid, but he's not nearly as good nowadays and I'd much rather have the newer Greven, Predator Captain instead, in all his Hatred-bearing glory
Unglued was not entirely a commercially successful expansion, but the unique basic land cards - the only cards from the set legal in tournaments - were and still are valuable
You can proliferate these, but it'll only matter if opponents try to remove counters one by one since a death trigger or trip to exile resets counters anyway
Then the turn after you played it, use that -3 ability and start the card draw
Those abilities will use that number in various ways
Even if the mythic itself was predetermined to be bulk, your brain still got to enjoy that half a second of "Oh boy, this just might be the Wan Shi Tong, Librarian I so desperately need," before finally peeling the Secret of Bloodbending