[MunchkinMan]

Normally, you can only have one Race or Mojo in play (Powers are limited by your Level and Power Ranks, which I'll come back to). The reason you can have any number of Items in play, even if you can't use them, is because the rules say so. Because the rules say the exact opposite about Race and Mojos, you can't play extras of those that you are not using.

Whether you understand this already or not, I'm going to cover Powers in detail, for everyone's benefit. Powers have Ranks. You may only use Powers with total Ranks less than or equal to your Level. So, at Level 1, you may only use one Rank 1 Power. At Level 2, you can use two Rank 1 Powers or one Rank 2 Powers and so on. You can not play Powers you can not use.