Jackal Lockdown is an old but still somewhat well-known deck, based on a similar draw lock as the infamous Yata-Garasu Lockdown. In this case, the lock is created by emptying the opponent's hand and destroying one of their monsters with "Mystical Knight of Jackal", returning it to the top of their deck to be drawn next turn. If the destroyed monster is one they can summon, next turn, they can either protect themselves by summoning the monster to have it be destroyed by battle again, thus ensuring the loop continues, or hold onto the monster in the hopes of freeing up their draw for a needed card next turn, in which case they've left themselves open a direct attack.