Affinity Friendly Valkyrie with 43
Note: Calculator currently does not show Valkyrie's passive TM gain.
Vakyrie must be 171 and the rest of the team between 187 and 189, with your fast champion at 252. This will allow Valkyrie to go last each turn while the rest of the team goes before her and still have a champ go at a 4:3 ratio.
UNM - Affinity
251, champion will go first/twice between the AOEs. Syncs from the very beginning. Use Sepulcher (or Duchess or other champ) Block debuff on turn count 1.
UNM - Void
251 needs to drop to 245 or 246 speed (1 or no speed sets with base 98 speed). Champion will go first/twice between the AOEs. Syncs turn count 7. Use Sepulcher (or Duchess or other champ) Block debuff on turn count 1.
251, champion will EVENTUALLY go first/twice between the AOEs. Sync's turn count 10. Use Sepulcher (or Duchess or other champ) Block debuff on 2nd attack on turn count 1 (A1, A1, A2). On turn count 10, delay the A2 skill 1 time till 2nd attack. You will have to navigate the stun until then.
For Void, 189 champion will go last and the comp syncs on turn count 7 - simply use the same delay as above, but on turn count 7 instead of 10.
Regardless of affinity this turn order will maintain. There is VERY little leeway with these speeds, so check true speeds.
"189" > 3/4*"251"