The GY effect of the Lv 2 Shiranui tuner specifically says “special summon” from the extra deck, not synchro summon. Plaguespreader is required material to SYNCHRO summon them. However, since Spectralsword special summons, it bypasses that requirement. I tried it online too just to make sure, and it works
You can’t summon revived king or the zombie skull without plaguespreader in the deck
The GY effect of the Lv 2 Shiranui tuner specifically says “special summon” from the extra deck, not synchro summon. Plaguespreader is required material to SYNCHRO summon them. However, since Spectralsword special summons, it bypasses that requirement. I tried it online too just to make sure, and it works