Malzahar lore theory
I have a theory: what if Malzahar hasn't actually sided with the Void, but is only "faking" it? I mean, let's analyze the situation: he is, as far as we know, the most powerful prophet in Runeterra (second only to Zilean, but he is practically a cursed god with the inability to influence the world, even if he is the most powerful being in Runeterra, so he doesn't count). He knows that the Void will come, but he also probably knows that they will fail the invasion. He is connected to someone in the Void, someone who constantly sends him malefic visions, but he chose to keep this connection because somehow this will lead to the Void fail. Maybe he had a vision and he saw that, to save Runeterra, he had to join the Void. Could it be?