As a three-mana legendary, this is extremely useful for aggressive Boros decks, and if you can find a way to grant it haste when it enters play, it only gets all the more dangerous
Knuckles the Echidna is an interesting card
All sixteen mainline entries will be represented with powerful spells, summons, and familiar locations
Any creature you control that can't be targeted by the copied ability (due to protection abilities, targeting restrictions, or any other reason) is just ignored
Then as this explores you'll draw lands or toss +1/+1 counters on this to grow it over time, and did you note the word missing here
The ultimate gift-ready box for any adventurer