I like the concept quite a bit. I think that I would swamp the bonus for zero enchantments and zero lands, since it's much easier not to have enchantments than lands, and indestructible is a greater payoff than trample.

Really, having zero artifacts and zero enchantments seems extremely easy - so this is usually already a 8/8 with some keywords.

Indestructible should not be among the keywords granted here since it provides so much of the benefits of a high toughness by itself that having both the toughness bonus and the indestructible keyword ability will be in many regards redundant - try to find something else from the pool of red-white abilities.

Only the first condition actually plays well with the flavor.

No zero planeswalker clause? ;)

I'm not certain whether this is top-down or bottom-up. Maybe both played a role in coming up with the design. I personally feel concentrating on the first ability seems like a better trick e. g.

> As long as you control no other creature ~ gets +3/+3 and menace and vigilance.
~ can block any number of creatures each combat.
~ gets +1/+1 for each creature your opponents control.
3/3

This is a quick sketch of what you can do with the concept of "Army of One".

The initial idea was "legendary creature that cares about what you don't have instead of what you do." The name was literally the last thing I came up with.

I agree about Indestructible being somewhat redundant, as well as no artifacts or enchantments being too easy. Maybe a a single +3/+3 bonus (plus first strike) for having no artifacts or enchantments? That removes indestructible entirely and makes it only a 6/6 first strike out of the gate instead of an 8/ first strike indestructible.

Huh, that's a really interesting idea. I think it might work better if it was rebalanced around things you were likely to run out of -- in most formats are you likely to get to zero land?

Maybe no other creatures, no cards in hand, no cards in graveyard? Or playing up the loner flavour, maybe no creatures cards in graveyard?

Hmmm. Different concept; but I kinda like the idea of something like "When you put a blah into play, if you control no other blah, then put a copy of ~ into play".

So it gets 'bigger' when you prove "Yup, I could be playing enchantments, but I chose not to"