The first thing that springs to mind about the Mutation Deck by Just Insert Imagination is that four Jokers just changes the dynamic quite a bit. For one thing, there is added value to Initiative Edges and Joker Edges and more triggers on the Joker's Wild setting rule.
I found myself using the deck in Necessary Evil 25 for the first time. I had a card flip for an encounter possibility and got 3 of Spades: Cold Affinity. This was interesting. First of all, it's not a Face card, so doesn't imply opposition. The cold affinity was a useful quality as the group was looking for a police van to steal. So they found a police van with a cold engine that hadn't been run recently.
So the card qualities themselves can be useful to use when drawing encounters. Like if drawing for an encounter, rather than just determining an encounter on a face card's qualities all the time, you could draw a second card to determine the quality of that encounter. The cold affinity above might help guide what kind of creature is encountered. A mage that uses cold spells? A cold terrain monster? An ice creature like a dragon or drake with ice breath? These can also extend to the other three different categories like psychic, bestial, and physical changes. Like drawing a card with sticky skin might be a slime encounter, a psychometry card might be encounter with a kleptomaniac thief who also has a psychic power to see into the power and history of items he touches and prizes only those items that trigger his ability, and spider limbs might be an encounter with giant spiders, a giant praying mantis with wallwalking, etc.
The one thing I think that might be the most useful part of the Mutation Deck in regards to Necessary Evil is the Death and Defeat Table. Those extra Jokers mean a much higher chance of the Transformed condition. But the Marked condition on 3-5 has some more interesting applications. Like if I drew 3 of Spades for Marked, you might end up with the Cold Weakness [Major] as your Marked-based Hindrance based on your card draw from the mutation deck. The player could always take the hindrance based on the Injury Table 2d6 roll instead, but this gives an additional option to the player for that Major Hindrance they gain as the part of the price for coming back to life. You could be highly sensitive to cold or lose an arm? Which Hindrance [Major] do you want?