Leprosy: I'm not entirely convinced it's unbalanced at 5 gems... but I can certainly see that the effects can be rather annoying and mm inducing, so maybe it would be for the best if it were cast less.
Early Blood summons: It's a tough situation, on the one hand I'm not sure even for current prices they will see much use early, on the other hand I can see the point that they might abusable late game (and by that I mean displace other spells). The issue is, mage time is too valuable to waste on them when you first research them, but once you have everything researched all the sudden you have a huge glut of mage time. I'm not sure there is a real solution to this, but I suppose I can mess with the prices a bit again.
Lord of the Gates: I'm actually really pleased to actually get a compliant about him... he has been stacking up boosts in vain since dom2.
Out of all the troop generating pretenders/heroes he gets by far the most, but I'm not quite convinced it's overkill. I've played against several people trying to leverage the shade spam, and it's usually not to hard to use the usual undead counters on them.