1. "Dark Hole" destroys all monsters with less than 1500 ATK on the field.
2. "Mecha Phantom Beast Dracossack" is destroyed by "Dark Hole" because its base ATK is also 1500.
3. The token monster, having less than 1500 ATK, is likewise destroyed by "Dark Hole."
4. When "Mecha Phantom Beast Dracossack" is destroyed, its effect triggers. It Special Summons a "Mecha Phantom Beast Token" to your field.
5. The "Mecha Phantom Beast Token" is immediately destroyed by "Dark Hole" since it also has less than 1500 ATK.
6. As a result of this chain of events, both your monsters are destroyed, and you're left with no monsters on the field after activation of "Dark Hole."