i'm kinda new and haven't played a draft yet cuz there aren't any tournaments here in the Philippines. sigh

Mill is a hold over term from Magic the Gathering(the first big tcg) that refers to effects that discard cards directly from the deck to the discard pile. The term "mill" comes from a card called millstone that was the first(or one of the first) with that effect. There are a lot of cards that mill in Destiny, but one of the premier decks that can mill right now is Jyn(from across the galaxy) & Cassian.

Aggro is an abbreviation of aggressive for gaming, it refers to an attack centric strategy for card games. In Destiny, a Melee centric deck like Kylo2/Pryce would generally be an aggro deck, since it prioritizes damage on an opponent and it includes cards to bypass removal(Force Speed/Tactical Mastery). Not every deck with Damage sides on die is aggro though, for instance "Naked" Palp was a deck that featured heavy removal over a traditional upgrade suite, so Palpatine's damage was the win condition but each round the primary goal was spamming removal to mitigate damage.

Atomisk pretty much got it. In his example with palpatine that would be what would be referred to as a "control" deck in Star Wars destiny, which is usually a deck that still wins through damage but focuses more on a steady burn while controlling your opponents actions, either through dice control, hand control or just straight action control.

thanks for taking the time out of writing that long comment atomisk. thank u to tunewalker