Omnimon

Q:I activated this card's [On Play] [When Digivolving] effect, and when my opponent's Digimon would leave the battle area for the 1st process, an immediate-type effect such as a "when [...] would leave" effect caused this card to be removed from the battle area. Can I then process the part of the effect after "then" in this card's effect?

A:Yes, you can. If an effect activates, it is to be fully resolved even if the card that activated the effect is removed from that area during the processing.

Q:When does a "when [...] leaves the battle area" effect trigger?

A:It triggers when a card in the battle area is placed in another area. The following areas are considered other areas: ●Deck●Digi-Egg deck●Breeding area●Hand●Trash●Security stack●Under a card (in a Digimon's digivolution cards or under a Tamer)

Q:Does a "when [...] leaves the battle area" effect trigger even if a "when [...] would leave the battle area" effect activates and prevents it from leaving?

A:No, it doesn't trigger.