How do you mean, "6
+ 1 card?" as a value for the card.
Much like with the occasional twin universe in Pandemonium, the sudden appearance of Flooding would be very unpleasant for the unprepared player. Personally, though, I'm not opposed to that.
Looking at the usefulness of the cards specifically, it is conceivable that a player could create a deck in which every permanent created would be useful to him (such as if he is just spamming permanents for FG's to burn their Explosions and Steals). The opponent, on the other hand, likely running dual-element as OldTrees pointed out, would run a 52% chance, per permanent, of a card suited to his element, based on my own humble calculations.
However, outside his element, most of these cards are usually useful. Any pendulum is at least somewhat useful. Unstable Gas and Sundial are useful to any player with a single Nova or Immolation played. Time (Hourglass) is used very commonly, even in decks designed for other elements.
So by gut (usually right where I work) I am predicting that a player's opponent would typically receive about 3 useful permanents. Some players would likely get nothing (Fractal Pests).
Opportunity Cost: Playing Antimatter for the same cost would essentially eliminate an opponent's creature while creating continuous healing for the player, which gives the opponent nothing in return.
Given this, I'm considering changing the upgraded card to 4
-> You receive two random permanents." This would allow the player the option of a card that does not assist his opponent at all (while still not necessarily assisting him, either).
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, even though you intend for it to be used in 
decks. Just the idea of a 
