Looks funky! I suspect it doesn't need to be 6 mana and 5 would do just fine, given that the Clone baseline was rather obsoleted by Phyrexian Metamorph being able to clone either creatures or artifacts for effectively just 3 mana.

The counter clause is interesting. I'm sure some fun things can be done with it.

Wow, the counter clause lets it ultimate immediately when entering as many planeswalkers.

Hm? I read it as only getting the number of counters that the source permanent had...

...Oh, except I see, yes, it does double the counters on things that say they enter with counters already, like Pentavus and, yes, planeswalkers. Yikes.

Oh, whoops. That definitely wasn't the intent. I thought copying a planeswalker would leave it with no loyalty counters, but I guess not. I hadn't thought about Pentavus.

It's six mana because it is the first card ever to copy any kind of permanent, and I wanted to play it safe. :P

Fixing the wording... but this card could have a case of "there's no fitting template".

You don't need to say anything about counters whatsoever. The only things that's going to help with are creatures like Mikaeus, the Lunarch or Nimbus Swimmer that enter with X counters, and most clones don't worry about those.

I don't know... it's a nice add. I'd have to say that without the counter clause, it's just a rare... an evolution of clone. Personally, I think it might be... shinier... if the counter clause was on a different line. But otherwise, I like it.

Yes, I quite like the original wording and the way it doubled counters.

The idea was that the card would pick up the counters you had been accumulating, for example, with Door of Destinies. It was never meant to duplicate counters (and if it did, it wouldn't have done it with the old wording, since only experienced rules guy would have picked up on that).