You kill their creatures, counter their cards, and delay the game long enough until you have the ability to kill your opponent with a single card or combo
What makes him very strong is his metalcraft to equip for free all day long if you control at least three artifacts, which is so easy since it counts lands and tokens, and with the card draw combined with that free equipping, he is an Equipment essential
After that, your opponent is forced to discard a card from their hand, a strong ability to run your opponent out of resources
The most important advantage Sire has over Koma is its mana cost
Whether its the pristine card quality or the cultural nuances infused into the design, owning Japanese Lorcana cards will likely feel like owning a piece of art
Having a consistent way to sacrifice your own creatures in this type of build is always important, especially if that sacrifice outlet doesn't cost you mana