One word added: random “enemy” targets. It would viable then. I got this damn weapon as my freebie, so I was greatly disappointed. A simple change would make this awesome. The randomness is fitting for Shaman, but at 8 mana it should at least not potentially kill your board.
Change it to: "After your hero attacks, Discover a spell with no targets, then cast it."
I remember it being mentioned on the stream when the card was revealed that Shaman have a lot of spells with no targets needed and those were the spells a player should look for when using The Runespear. If that's the case, why not just limit the card pool to just those cards.
It could also be: "After your hero attacks, Discover a spell and add it to your hand. It costs (0)."
A much more flexible option. You could search for removal or lethal right away or save the cards for later when you need them.
They could start with a really minor change: allow you to choose "none of the above".
There's a fairly decent chance each time that you're given three options that are either 100% detrimental to your own board (like Volcano) or have a high likelihood of hurting you (any single target damage spell). The reward isn't great enough with the current pool of Shaman spells, so taking the risk out of it seems like the least they could do.
It's kind of ridiculous to talk about the relative power or fairness of The Runespear in a meta that has no strong Shaman decks. Shaman needs a lot more power across the board to be competitive, and The Runespear isn't intended to be the centerpiece of any deck, so changing it won't drive Shaman forward.
Maybe the player should be able to choose between these four options. 1. Only enemies 2. Only friendly 3. All targets 4. No targets. And no overload, because the wespon itself cost about 4,5 mana more.