As one of the most anticipated new mechanics in years, mutate has some high expectations to live up to
Giving all your other characters 3 extra Strength is nothing to be scoffed at
Effects that modify a creature's power and/or toughness, such as the ones created by Giant Growth, will apply to the creature no matter when they started to take effect
At the very least get that first quote then post your collection on Facebook Marketplace ( or whatever local platform ) with good pictures and see what interest you have and if theyll pay more then the store
Anytime a creature deals combat damage to an opponent, that creatures controller can pay one life to draw a card
However, its mighty wings have yet to fly very high in Constructed formats, except in some Boros reanimator shells alongside Fable of the Mirror-Breaker and Invoke Justice