Marvel War of Heroes Special Assignments:
Batch 1: Unlocked at start
Battle Once - 1 Personal Power Pack
Attack and win 2 times in a row - 2000 Rally Points
Attack successfully 3 times - 30,000 Silver
Steal 2 resources - 1 Shield Barrier
Attack successfully 5 times - 1 Personal Power Pack
This batch was really easy once I stole two resources using my full attack deck. Afterward I placed two cards in my deck and looked for people I had previously marked as having 10 defensive points and farmed them five times. Once they are all finished you receive the (Leopardess) Tigra card which is a rather weak SR.
Batch 2: Unlocked after Batch 1 is complete and after November 24th
Battle 2 times - 1 Personal Power Pack
Activate 2 skills in Battle and win - 4000 Rally Points
Win with raised morale - 50,000 Silver
Attack successfully 10 times - 1 Personal Power Pack
Attack successfully 20 times - (Level Up) ISO-8
This batch is more time consuming but still follows the same principle. Four of the five achievements can be completed easily by farming people with 10 defense with a one or two card deck. There are a lot of high level farming accounts with 10 defense. The activiate 2 skills in a battle and win is also easily completed and in most cases should occur naturally using a 2 card deck as long as they both have skills. Once they are all finished you receive the second (Leopardess) Tigra card which can be combined with the first card.
According to the special assignment description (Leopardess) Tigra is supposed to help somehow in the following event so I wouldn't say trade her away or toss her yet. Although a lot of the events in Marvel War of Heroes parallel Rage of Bahamut, it's possible Mobage adds a little bit of a twist on the events. Kind of like the rotating alignment for bonus damage when attacking Loki. It's possible they are doing something along those lines with Tigra.