Voldaren Bloodcaster // Bloodbat Summoner

Blood tokens that become Bats with Bloodbat Summoner’s ability are still Blood artifact tokens and still have “{1}, {T}, Discard a card, Sacrifice this token: Draw a card.”

If an effect refers to a Blood token, it means any artifact token with the subtype Blood, even if it has gained other subtypes.

Some triggered abilities trigger "whenever you sacrifice a Blood token." These abilities trigger regardless of why you sacrificed that Blood token.

Voldaren Bloodcaster’s last ability checks how many Blood tokens you have both as it triggers and as it resolves. If you don’t control at least five Blood tokens at both of those times, it won’t transform.

You can't sacrifice a Blood token to pay multiple costs.