I can't solve the Phyrexian Obliterator puzzle. It's a pretty irritating puzzle, I don't think I'm close to solving it.
Oh, actually. I just had an idea. The blink effect doesn't just remove Arrest.. it removes +1/+1 counter from your creature, allowing it to use Undying an extra time. [edit: Nevermind.. the blink effect is the very first action you must take to do anything else. Ugh, how is this puzzle even solveable!!]
You can force the Obliterator to attack but I don't see the point of this. I also wonder if the first strike effect has any purpose. What's confusing about these puzzles are the red herrings. (the cards you don't need to solve the puzzle) It would be easier if those weren't there.