Sin enters with X +1/+1 counters on it, where X is twice the number of counters removed this way
Even if you dont play the game, Id say these cards are worth it just for the beatiful art on display
Unsurprisingly, this gets even better when the rest of your deck cares about enchanting creatures, as the Silverquill Influence precon does
The rules for said step read as follows: Second, the following actions happen simultaneously: all damage marked on permanents (including phased-out permanents) is removed and all until end of turn and this turn effects end
If it's the first combat phase of your turn, there is an additional combat phase after this phase
Though eventually you can turn it into a flying machine, as seen in the art for Ancient Adamantoise, where it's about to get chomped and taken back to the shop for maintenance yet again