As an Ogre player myself, nothing is as scary as Lore of Shadows. Pit of Shades can cause horrific damage to his army even in the short time it takes the Ogres to get across the board to you, and most of the other spells help even after combat starts.
There's two spells you need to shut down if he's using Greedy Fist + Death: Caress and Fate of Bjuna. The signature spell does wounds, not hits, so let it through. Shut the other spells down with Becalming, scroll, cube, etc, then get the Slann's unit into combat where he can't cast direct damage spells at it. That's when your Shadow hexes/mindrazor comes into play, and your saurus/temple guard can gain their advantage.
If you see the Death wizard off on his own, beware flying carpet/purple sun hijinks. Activate Skink Defense Systems, and keep Becalming on him.
Mournfangs are scary powerful, and super fast. Definitely a priority target; guard your flanks! They've great armor, so skink shooting is much less effective.
The "miscast rolls" caused by the Hellheart item are still very much debatable. The Ogre book uses the terms "miscast" and "roll on the miscast table" interchangeably in the item description (even in the same sentence), so I've always allowed Throne of Vines, etc. to offer protection against it. YMMV though, so be prepared to argue depending on your opponent.