All hail the Boar God!
The most talked about combo in town is the one when you get to put Emrakul on the battlefield tapped and attacking.
Since there are entire archetypes based around putting Emrakul and other ridiculously powerful creatures on board, Ilharg will definitely see play as that extra damage pusher.
There are simply no drawbacks with Ilharg. It's simple and effective, and that's what most players are looking for.
Depending on how good it will perform there is a big chance that Ilharg will rise in price, and there is no real way to say when it will stop. But this is definitely one of the most investment friendly cards in War of the Spark.