The most harmless spells in Harry Potter are generally considered lighthearted charms like Rictusempra (Tickling Charm, causes uncontrollable laughter), Tarantallegra (Dancing Feet Spell, makes legs dance uncontrollably), or Cantis (Singing Charm, forces a sing-along), designed for pranks or minor annoyances without causing real injury or lasting harm, though even these can be disruptive in a duel.
The really useless/worse than useless Harry Potter spells
The three curses that are classified as Unforgivable are the Imperius Curse, the Cruciatus Curse, and the Killing Curse. Mad-Eye Moody introduces Harry and his class to these curses in Harry Potter and the Goblet of Fire.
Its incantation is Avada Kedavra. The only known counter-spell is sacrificial protection, which uses the magic of love.
Page 394 in Harry Potter and the Prisoner of Azkaban refers to Professor Snape telling the class to turn to that page in their Defense Against the Dark Arts (DADA) textbook, which is about werewolves, a deliberate hint that the substitute teacher, Professor Lupin, is one himself, a secret Snape was trying to expose. While the specific text varies slightly by edition, it introduces the topic of werewolves as nocturnal beasts, contrasting with the Red Caps and Hinky-Punks they were learning about, to reveal Lupin's true nature.
By itself, Meteor Swarm is probably the biggest chunk of damage, dealing 140 on average or 240 if you miraculously roll max on every die. This is dealt to every creature that fails their save in a LARGE area, so the total damage gets really nutty on groups of enemies. Single target and adding in other effects?
The Unforgivable Curses consist of three Dark spells that are illegal. Each of these spells are incredibly powerful and mostly wielded by Dark witches and wizards. They are the Killing Curse, Imperius Curse and the Cruciatus Curse.
The rarest wand wood of all, and reputed to be deeply unlucky, the elder wand is trickier to master than any other. It contains powerful magic, but scorns to remain with any owner who is not the superior of his or her company; it takes a remarkable wizard to keep the elder wand for any length of time.
The counter spell to Lumos, Nox extinguishes light from the end of the caster's wand. The incantation comes from the Latin for 'night' or 'darkness'.
In Harry Potter, the "Three D's" are the crucial principles for successful Apparition: Destination, Determination, and Deliberation, taught by Ministry instructor Wilkie Twycross to sixth-year students. Mastering these ensures you reach your desired spot without "splinching," a dangerous mishap where body parts are left behind.
Accessed through an abandoned red telephone box the Ministry can be reached by dialling 62442 (which spells 'MAGIC' on an alphanumeric keypad).
The worst curses known to wizardkind were the three Unforgivable Curses; the Cruciatus Curse which caused the victim excruciating pain, Imperius Curse which made the victim totally obedient to the caster, and the Killing Curse, which instantly killed the victim.
The level 12 spell: Karsus' Avatar.
Attack roll spells are functionally the same as any other attack and are made against your ac, everything else uses a saving throw instead. The spells either target something by tracking them and trying to hit them with the spell, or they simply have to resist the effect via a saving throw.
While the Harry Potter books themselves feature themes of fighting prejudice and acceptance, the question of whether the franchise supports LGBTQ+ issues is complex, largely due to author J.K. Rowling's public statements and activism, which have been criticized as transphobic by LGBTQ+ advocates and even some Harry Potter stars like Daniel Radcliffe and Emma Watson, leading to a split between the books' themes and the author's personal views.
Vault 713 was a high-security vault at Gringotts Wizarding Bank in London, England.
The Laceration Curse (Sectumsempra) was a curse invented by Severus Snape that lacerated the target and caused severe bleeding.
The Killing Curse (Avada Kedavra)
One of the three Unforgivable Curses outlawed under wizarding law, Avada Kedavra kills the victim on impact, instantaneously and painlessly, usually with a blinding flash of green light. There is no way to block the spell, and there is no counter-curse - it can only be dodged.
Voldemort met Nagini, a Maledictus (a woman cursed to become a snake), during his exile in Albania after his first defeat, likely in the forests there, where she was already a massive snake. He found her while possessing snakes to survive, and their connection grew due to his Parseltongue ability and her unique ability to sustain him, eventually leading him to make her a Horcrux by killing Bertha Jorkins in 1994.
Abracadabra is suppose to mean in Hebrew, "I will create as I speak", or in Aramaic, "I create like the word" (אברא כדברא). So in a sense, Abracadabra is the opposite of Avada Kedavra, which kills, while Abracadabra is suppose to create.