If the flicker player cannot get some valuable targets onto the battlefield and keep them there, they cant reach that efficiency breakpoint where they begin recurring high-impact ETB triggers to advance their board at instant speed instead
For that reason, Id include a fair amount of artifact mana cards that cost three mana, like Darksteel Ingot
It's basically a build-your-own-combo card, but also has the very unique effect of taking on the triggered abilities of other cards, something I only recall seeing on Idris, Soul of the TARDIS
Once a creature is exiled by the reflexive triggered ability, it doesn't matter what happens to Auron's power
Song of the Dryads, one of the best green removal spells, and Lignify are similarly strong for this slot
With that said, at the time of this article, the Worlds Smallest Magic the Gathering Duel Decks are very limited in supply