The MANNERS of acting, in grammar called modes or moods, are four; Infinitive, Imperative, Indicative, Subjunctive or Conjunctive.

Jeff winked his eyes sleepily open and looked out into the cool flush of early morning. The east was oranged over with daybreak.

This world I do renounce, and in your sights Shake patiently my great affliction off.

McGonagall is earnestly trying to gather the resources of a metrical tradition, not subvert it, but the mismatch of duple and triple measure in the first line alone means that, while it’s made of recognisable metrical feet, the line doesn’t feel like it belongs to any specific metrical pattern (iambic, dactylic, anapestic etc) or mode (pastoral, elegy or ballad).