Keep in mind that their whole lore can be cast on a 3+. In many cases, Ogre players can attempt to cast spells on one Power Dice each to get as much mileage out of their spells and negate the risk of miscasts. If they end up rolling a five or a six, then you'll be prompted to throw two dispel dice for one power dice. If this pattern keeps repeating, then there's a good chance that they can get a crucial Trollguts or Toothcracker off through your defenses, even though you have a dispel dice advantage. So, I'd treat them much like Vampire players - only worry about spells that are going to directly affect your units while engaged in combat. Ogres can also cast multiple Remains in Play spells.
The tradeoff in this is that many of the Ogre spells have a chance of wounding their Butcher, so I frequently allow them to cast their spells on unengaged units with the hopes of wounding their casters. Their lore is very short ranged, so expect friendly buff spells to be cast primarily on the Butcher's unit or one right next to them.
Lastly, DON'T FORGET YOUR MAGIC PHASE!! Go on ahead and announce it out loud. You'll feel pretty stupid doing it, but it's the best way I've found to remind myself that I have Power Dice of my own to use to get rid of Remains in Play spells. A Magic heavy list will have many RiP spells on the board, and it'll take a 7 to dispel one- relatively easy to accomplish with 2 Power dice. The Master Rune of Valaya may also be worth looking at, since those RiP spells will go 'poof' once they engage your units.
Now, onto the lore list:
Bloodgruel - On a 2+ the Caster heals a wound. On a 1 he wounds himself. Not a big deal of a spell, but it becomes more important during the late game after a couple self-inflicted wounds. I've had casters attempt to cast this spell early on a Wounded butcher to sucker me into dropping more dispel dice than I should. 1- 2 beers.

Braingobbler- Force an enemy unit to make a Panic test. This isn't something we typically worry about, but a favorite item of Butchers is the Skullmantle, which will reduce the target unit's Leadership by 1. Be prepared for Leadership 8! 1-2 beers.

Bullgorger - An Ogre unit gains +1 Strength. This bonus will also improve Bull Charges, which is an Ogre Player's answer to evening out combat resolution in their favor. This is important to dispel on the first round of combat, but afterwards you've more important spells to deal with. 2 Beers.

Bonecruncher - The magic missile spell of the Lore. This spell ignores armor saves, so it has some potential for hurt. 3 beers.

Toothcracker - my personal worst spell in the lore. This grants an Ogre unit +1 Toughness and Stubborn. Suddenly those Ogres can ignore combat resolution! Expect the General's unit to be targeted by this spell frequently. 4 beers- This is something you need to hang onto Dispel dice for.

Trollguts - Grants an Ogre unit Regeneration and MR 2, like a Stone Troll. MR2 means nothing to us, but Regenerating Ogres can be the bane of a shooting army. 2 beers for a 'balanced' army, 3 for gunlines!
