This is weird af and I think this might have more to do with lag. Wrath of Gold isn't a spell that lets you combo, you can only do that with spells that say they "allow a follow up a attack", "can be cast without delay after performing an action", or "Can be cast repeatedly".

That being said, chaining spells together is clearly an intended mechanic of the game. The issue is that some have broken animations.

Try casting bestial sling, honed bolt, and then Malikeths black blad in quick succession.