BARDBACADABRA I. Spells are woven by weaving words into formal verse. Every spell must describe an effect and name a target. Every particular combination of words only works once, ever. More complex spells require more elaborate verse forms. CANTRIPS. Rhyming couplet, with any syllable count. GLAMORS. Haiku. ARS ELEMENTA. Heroic couplet. MINOR CONJURATIONS. Limerick. BEWITCHMENTS & ENCHANTMENTS. Heroic stanza. DIVINATIONS. Couplet in trochaic octameter or hexameter. HEALING. Rhyming triplet. WEATHERWORKING. Quatrain in dactylic hexameter. BLIGHTS & HEXES. English sonnet. BLESSINGS & BUFFS. Italian sonnet. DEMONOLOGY. Rhymed acrostic, naming the spirit. SUBSTITUTIARY LOCOMOTION. Ottava rima. TRANSMUTATIONS & TRANSFIGURATIONS. Fourteener triplet. MALEFICIENT MINSTRELRY. Fornyrðislag. ABJURATIONS. Skeltonics. MAJOR CONJURATIONS. Villanelle. NECROMANCY. Rondel. MIRACLES. Ballade. II. Spells that will cohere well with your wishes are: A spell whose sound is an echo to its sense. For the short spells, neat and polished. For the long, mellifluous and fleet. III. To cast a spell that fails to kindle, or twitches then dwindles, or blazes then mutate, or bewitches an ally, or spills into the world filled with glitches: Rhythms that stray unaccountably from metre. IV. They say the bards of the far northern isles practice a quite different art, that some call the Open Field.
A heroic couplet is two rhymed ten-syllable iambic lines. Wikipedia can help fledgling bards with most of the terminology. Or consult grimoires such as Philip Hobsbaum’s Metre, Rhythm & Verse Form, or Derek Attridge’s Poetic Rhythm (and many other books by Attridge). For even deeper arcana, consult JH Prynne, Stars, Tigers and the Shapes of Words, and Simon Jarvis, Prosody as Cognition. Also see Alexander Pope, Essay on Criticism. The supplement alludes to the Open Field School, but of course there are MANY other schools of bardic magic.