Two problems:

1. Solemn Wishes doesn't have a mana cost, so it can't be cast. Cards without costs aren't free in Magic, they're actually uncastable by normal means.

2. LP isn't health in Magic. It's called Life. So yeah, you'd gain 500 LP, which would be some kind of spendable currency like energy, but you'd have nothing to spend it on, and it wouldn't do anything to your life total.

Yes, I am really fun at parties.