Oh, you have to Summon an equal number of monsters to the number of materials detached for Tallyho’s cost.
This interaction is similar to Lumina, Lightsworn Summoner
’s effect discarding a Lightsworn
monster: you CAN Summon the monster her cost discards, but you must already have another Summonable Lightsworn
monster in GY before you are allowed to even activate her effect. Source