1. First, you can upgrade directly with Otto kernel. Click the upgrade level in the combat hero interface. There are three ways to obtain Otto's core: dropping off customs clearance, rewarding for completing tasks, and directly recharging for purchase.

2. The second method is to look at advertisements to get promotion opportunities. Click free upgrade in the above interface, and there will be a channel to watch advertisements. There are several opportunities to watch the advertisement upgrade every day. This method is more cost-effective and time-consuming.