Welcome!
Glad the hellheart worked out for you, it has brought me nothing but failure (but I don't have alot of VC in my local scene) - of course I have gotten new dice since then 
Since you're here and you've volunteered such information, from the perspective of High Elves and WoC, whats your most/least feared Ogre unit?
Thanks for all the nice replies guys. Yes, the hellheart definitely did its job in both games for me, it will definitely find a place in my list against VC from now on. Heck, any magic heavy army who tends to cluster their mages together will enjoy a hellheart from me I'm sure.
As for your other question, I haven't had any games yet against my own OK army, but I did play against my own high elves for the 1st OK game I ever played so I can try to offer some perspective in that regard.
Against WoC-
Ogre bulls are a joke against WoC core warriors. 20 warriors with halberds/nurgle will hit your bulls on a 3 and wound on a 3, with 16 attacks coming your way before you get a chance to retaliate, hitting on 5's and wounding on 4s. Without some hexes or augments, you're fighting a losing batle.
As a WoC player, I fear war machines and shooting heavy armies- to that end I would suggest a gunline against WoC. Leadbelchers will wipe chaos warriors off the face of the earth very quickly (Str4 AP means that without a shield they are looking at a 6+ AS), and those ironblasters will make short work of any character without the mark of Tzeentch and third eye. Never, ever bother shooting at a Warshrine- any decent player will kit it as tzeentch for a 3+ ward save.
Against High Elves-
I had a miserable time against the high elves, my buddy went with a flying circus army (3 nobles on eagles and a frost phoenix). There was pretty much no defense as he tore into my flank and onwards through the rest of the army. Even with OK great MS it is nearly impossible to avoid and redirect something like that.
Playing them from the opposing side I learned to fear that frost pheonix- it thoroughly ruins your combats with its -1 Strength and even a well placed cannonball has a chance to bounce off of the thing (with a lucky WoM roll the thing can have a 4+ ward). The biggest nightmare you will ever face against HE is a white lion horde backed by the Everqueen. that's 40 s6 attacks striking on initiative with magic attacks, then they have a 3+ AS vs. shooting, a 5+ ward vs non-magic, and a 2+ ward vs magic. If the Everqueen is Lore of High Magic that non-magic ward can be buffed to 3+! I don't see much you can do to a unit like that besides dwellers or Purple sun or hope they are dumb enough to charge gnoblar trappers over and over.
As a high elf the scariest unit to go up against without that lion horde would be a big block of ironguts- you know that every one of their hits, impact hits, and stomps will most likely kill an elf- so you need to really stack the odds or roll well to win on CR. Again, leadbelchers can chew through the pathetic armor of the elves and really cause some havoc. Elves cost a lot of points so dropping even 5 PG/WL/SM per turn with your leadbelcher unit can work wonders.
I'm sure I'll have more insight as I play more games, but if you guys have any more specfic questions for me just let meknow, I'm happy to help!
