Here's how it works:
* Wall of Illusion's effect: It's a Continuous Trap Card that negates the attack of a monster that declares an attack on the player it is controlling.
* Going back to the hand: Wall of Illusion's effect is only triggered *once* when a monster declares an attack. It does not continuously negate attacks. Once the effect resolves, it's treated like a normal Trap Card – it remains on the field unless it's destroyed or banished by another card effect.
To summarize:
* Wall of Illusion negates one attack.
* After that, it stays on the field.
* It doesn't negate the next attack or automatically go back to the hand.
Let me know if you have any other card questions!