I had used Forbidden Chalice to remove Yubel's 2nd form abilities then destroyed it in battle. But even though it got wasted in battle without its effect, it still somehow retained its effect of when leaving the field, to summon Yubel's 3rd form.
The card text states this is when it LEAVES the field. So if its still considered on the field when this effect should resolve, why is it activating when its effects are supposed to be negated?
"When it leaves the field", means its effect activates on the location where it is sent (hand, grave, or banished area). NOT the field (where Chalice is active). If any card can stop the activation, it's cards like Debunk (if sent to the grave or hand).
You literally awnser your own question man.'when it LEAVES the field' meaning while its in the graveyard or banished. For example if you use a card that destroys it the summon of the next form happens whilst in the graveyard. Now if you use lets say divine wrath when its effect activates in the grave it will stop the effect.
Yubel's effect activates in the graveyard.
Chalice negates monster effects while they are on the field, and no longer affects them when they're in the graveyard.