In Afterpulse, weapons can exist in ranks from 1-star up to, and including, 7-stars. Certain weapons only exist in higher stars based on their rarity - Alpha, Bravo, Charlie, Delta, and Echo. Check our other guides or videos for more info on rarities, or tiers.
When opening crates in the game, players can receive 1- through 6-star weapons. Players can then use the Power Up option to level up each gun. It takes more resources to reach max level in accordance with its number of stars.
Once a weapon has reached max level, it can be Evolved or Combined. For info on the Evolve option, check our other guides or videos. This guide will focus on Combining weapons.
The Combine option is accessed by going, from the Home Screen, Inventory->Fusion->Combine. Alternatively, players can go, from the Home Screen, Inventory->Tap the 'i' icon on any weapon->Fusion->Combine. With the latter option, the selected max-level weapon will be placed in the Combine UI. Therefore, the latter option is recommended as it can be quicker. If you chose the further option, you will have to tap one of the open weapon slots in the UI and select your max-level weapon.
Now that your max-level weapon is in the UI, there are just two other things needed to follow through with the Combine - Cash and Burners. Further info on both of these are listed below.
Assuming you have the appropriate Cash and the extra weapons needed ('burners'), then go ahead and hit the Combine button. Be aware that once this is done, there is no going back. Your max-level weapon will no longer be in your inventory - neither will the other weapons you selected. Instead, you will receive one new weapon that will be one star higher than the max-level weapon you used. For example, Combing a 4-star will generate a random 5-star. Note that the new weapon will always be at level one.
That's the basics of the Combine option, but there's a bit more info you should know.
First, weapon rarity affects what you can receive. If you Combine a 1-star, you will never receive a Bravo, Charlie, Delta, or Echo weapon since these don't exist at the 2-star level. If you Combine a 2-star, you will never receive a Charlie, Delta, or Echo weapon. And so on, so on.
Second, you can only receive weapons that would normally be available in Military Crates or Restricted Crates in the Shop, unless there is an ongoing special event. Check the Events menu (accessed from the Home Screen), to see which events are active. If there is no event active, you will never receive a skinned weapon (a series variant of a weapon - for example, A 500 Dragon, FAR N Panther, etc.).
If there is an active event, it will most likely include one series at a time. You should check the odds - some events are 100% chance while some are less. You should also check the star levels available - most events only include 1- to 4-star Combines. This would mean that if you Combined a 5- or 6-star weapon during such an event, you would have 0% chance to receive a skinned weapon.
Lastly, there is no effect on outcome based on which max-level weapon is Combined, nor what materials are used in the process. This is a very common question, especially for new players. After several years of experience, there's no evidence to suggest that this would be true.
That's it! To sum it up in one line: Combine trades one max-level weapon for a random weapon that is one star higher. For quick references on the needed material, check below. Best of luck!
Note: You can't Combine a 7-star as there are no 8-star weapons in the game.