Getting to draw cards at instant speed is always the best way to draw cards, and packaging it with the option of a team-wide buff instead makes this card a slam dunk
Im also not a huge fan of Surgical Extraction if you have no way of getting Krark-Clan Ironworks in a graveyard that isnt Natures Claim and then kill them on my next attack, as its largely a two-card combo then, but its worth a bit more examination
A tech choice that has been performing very nicely is Bazoo The Soul-Eater
For example, if you control The Ozolith ("Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.") when Sin's last ability resolves, you'll put the appropriate number of each kind of counter onto both The Ozolith and the target creature
Ten stacks means that you can fit 4,370 cards in one of those boxes
One (1) Special card