You cannot activate this effect during a turn in which you activated the effect of another card, and that activation was successful but its effect was negated
Although it will be unable to attack during the turn in which it's played, you can use your Leader's effect to swap its power with a Character played on a previous turn, allowing that Character to attack in its stead
With Vise restricted, both cards and the decks that resulted caused even more trouble than the Vise had in the past
If the card states 'until the end of the Digimon's lifespan', the card remains in the slot even if your Digimon evolves or is sent to the Dark Area not via reaching its lifespan
There also arent any dual tap lands to help with the mana base
Its designed for Fusion Strike first, as its attack does more damage with that special energy card, but colorless energy requirements mean it might see some play in peculiar scenarios and its a real boon in limited play