When you need animations longer than 2 seconds that function more like short films than UI transitions. This covers cinematic techniques adapted for web: multi-phase easing curves, full squash and stretch at 40%+ deformation, 400-600ms anticipation builds, and orchestrated secondary motion across 120+ frames. The guidance is properly opinionated about requiring skip buttons, showing once per user, and budgeting 3-5x normal dev time. Best for product launches, milestone celebrations, or premium onboarding where the animation is the experience itself. Treats this duration tier seriously as mini-productions requiring storyboards and stakeholder buy-in rather than pretending you can wing a 3-second animation.
npx skills add https://github.com/dylantarre/animation-principles --skill dramatic-2000ms-plus