In Far Far West, leveling spells is essential for unlocking advanced abilities, including the final spell in each line at level 35. Players can earn XP by frequently casting spells rather than focusing on kills. The first method involves using level one spells during missions, as they can be cast more often due to shorter cooldowns. Notably, the Mino spell from the Cactus line has an 8-second cooldown, allowing for rapid casting. The second method leverages Nightmare mode, where players can earn a 200 XP bonus for the first use of each spell in a session. By casting all available spells and then intentionally dying, players can quickly reset and accumulate XP without waiting for cooldowns. This approach can yield impressive XP gains, with players reporting up to 475 XP in a single attempt, showcasing the efficiency of these strategies.