This command block structure adds in a series of magical weapons.

Copy and paste these commands into chat to give you the items:

Fire Bow: /give @p minecraft:bow 1 0 {explosive:1b}

Fire Charge (drop to use): /give @p minecraft:fire_charge 64 0 {fireCharge:1b}
(based off of jragon's, similar but different, slightly less glitchy)

Wither Spell (drop to use): /give @p minecraft:skull 64 1 {witherSpell:1b}

Fire Spell (select in hotbar): /give @p minecraft:carrot_on_a_stick 1 0 {fireSpell:1b}

Lightning Spell (right click while entities are between the circles): /give @p minecraft:carrot_on_a_stick 1 0 {lightningSpell:1b}

Fireball Spell (right click to use): /give @p minecraft:snowball 64 0 {fireBall:1b}