I think The Runespear might be broken. I've only used it once, but doing so crashed my game. (I had Tunnel Trogg active, I was trying to grab Healing Rain, and the attack I used was an Overload attack, but I suspect that none of that information is relevant.) The crash happened right as the card went into my hand (which makes sense, as that's when The Runespear would try to update the card cost, which seems to be the sticking point), with the following stacktrace:

Exception in thread "LWJGL Application" com.badlogic.gdx.utils.GdxRuntimeException: java.lang.NoSuchMethodError: com.megacrit.cardcrawl.cards.AbstractCard.modifyCostForTurn(I)V
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:133)
Caused by: java.lang.NoSuchMethodError: com.megacrit.cardcrawl.cards.AbstractCard.modifyCostForTurn(I)V
at thrallmod.actions.TheruneAction.update(TheruneAction.java:38)
at com.megacrit.cardcrawl.actions.GameActionManager.update(GameActionManager.java:179)
at com.megacrit.cardcrawl.rooms.AbstractRoom.update(AbstractRoom.java:325)
at com.megacrit.cardcrawl.rooms.EventRoom.update(EventRoom.java:28)
at com.megacrit.cardcrawl.dungeons.AbstractDungeon.update(AbstractDungeon.java:2532)
at com.megacrit.cardcrawl.core.CardCrawlGame.update(CardCrawlGame.java:871)
at com.megacrit.cardcrawl.core.CardCrawlGame.render(CardCrawlGame.java:419)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:225)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:126)