Eternal Witness is in my top 5 favorite cards of all time, and Im glad Wotc has given the OK to ETB effects being able to bring back any particular card in the graveyard instead of sticking with sorceries like Treasured Find
While its escape cost of four mana and five exiled cards from its controller's graveyard allows its 6/6 body to be used in combat, even if it is immediately sacrificed, when it enters the battlefield or attacks, each opponent discards a card they lose three life if they can't
a 3/3 green Ape is nothing big in a 40 life format like Commander, so its a fine trade for removing a commander or important combo piece
If Iron Apprentice has -1/-1 counters on it when it dies, the last ability will include those as well
Opening a pack is also pretty immersive since you have to trace the line on the pack to open it
Your five mana instantly will draw you five cards