Check out our Marvel's Avengers Game 2020 guide on how to get Optic Decoders, required item to complete mission chains.
What's Optic Decoders
Required Item To Complete Mission Chain
Some mission requires you to collect Optic Decoders to complete mission chain. For example, Iron Man's Iconic Mission chain Global Mission Objectives' objective is to collect 3 Optic Decoders of Riotbot.Check Out All Iconic Mission Guides From Here
How To Get Optic Decoder
In order to get Optic Decoder, you simply have to defeat the designated enemy and pick up its dropped item. For example, if you need to collect the Optic Decoder of Riotbot, you need to defeat Riotbot and pick up its drop item. Look for a white shining drop item after defeating enemy.