Swordsoul is a crazy new Synchro archetype that is very consistent. Your main starter is either going to be Mo Ye, as he can one-card synchro into Chi Xiao which gives you a search AND Mo Ye draws you a card on synchro summon, or Eccclesia, who can tribute herself to special summon Mo Ye, and start your combos from there.
The D/D engine is in here to go into Halqifibrax plays and to dig deeper into the synchro pool, however, it's not as consistent as just the Swordsoul engine is. When it goes off, you can end on some devastating boards, but if you prefer to use a pure Swordsoul engine, the side deck is catered to taking out the D/D engine, and just using generic handtraps and removal.
There Can Be Only One is a great tech option for games two and three, as your ideal end board will have no more than one type of monster on the field, and can completely shut down monotype archetypes you may be facing.