Of course, if a player has an instant spell with enough untapped mana or a mana ability on a card already on the battlefield, the aftermath spell can be thwarted in some way
The efficiency of your combo is a question of how many pieces there are to your puzzle and how easy those pieces are to assemble
Pumping more mana into flickering or cloning Agent of Treachery is a win condition in many decks
You'll be able to use this on turn two most times, and almost any time you have a target in your graveyard worth recurring, you'll have the mana you need to get it
There are tons of other synergistic engines like Goblin Welder, Daretti, Scrap Savant, and Goblin Engineer to fit in all kinds of combos and interactions into the list
Whenever an Archer you control deals damage to a creature, you may pay