From Sphinx of Uthuun to Consecrated Sphinx, from Ulamog, the Infinite Gyre to Liliana of the Veil, and from Mind's Eye to Survival of the Fittest, you can copy anything
For maximum value, I like the elf token copy and untap + mass pump, but even if you don't have a great elf in play, the other two options can pull you out from a losing situation
#1 Burgeoning If theres one green ramp spell I want in an opener, its Burgeoning
1x Starter Deck - (Official Japanese product brand new)
It creates an awkward scenario for your opponent because they either have to trade off one of their own creatures or removal spells for it, or else they risk allowing you to accumulate value
Since Captain America will have high stats and multiple abilities granted by Equipment, it is very easy to deal 21 combat damage to an opponent to take them out of the game through commander damage