The value of this card is primarily in that it's a "only slightly worse dunland crebain that deals an extra damage or two", the massive upside turn where you steal their thing and sac it to improvised club is the icing on the cake
Activate this ability only any time you could cast an instant
I started the key turn by killing Jodah with a Rapid Hybridization
Narset can grab instant and sorcery spells, which is great, but it can also grab planeswalkers, enchantments, artifacts, and battle cards from any player's graveyard, not just yours
Then, for seven generic mana, you can "Timey-Wimey" it right into play by time traveling three times
Doubling Season does not care about the type of counter put on your permanents