Flash - Advent: Dark Snake & Cost 3 or more (Either Attack Step)
By sending your Soul Core(Soul Core) to the Trash, stack this from your hand onto your target spirit.
[LV1][LV2][LV3] (When Advents) From your hand/Trash, you can summon up to 3 Cost 6 or less "Dark Snake" family Spirits/Braves without paying the cost.
[LV2][LV3] (When Attacks) During this turn, your "Dark Snake" family Spirits cannot be blocked.
Rulings: Since Grandwalkers' Core Charge activate by timing instead of the amount of Spirits summoned, when you have "The Grandwalker Osiris" on the field and use this card to summon more than 1 Dark Snake, the Core Charge effect will only increase 1 core.