Syrus summons to the field Drillroid and has it attack the Gate Guardian in defense mode, but is blocked by Defence Wall because of its effect, and Defense Wall is destroyed. Because of this, Jaden and Syrus lose 500 Life Points. While it does seem logical that their life points would go down because Drillroid has 1600 attack points and Defense Wall has 2100 defense points, they should not lose life points in the first place. This is mainly due to the fact that Drillroid's effect causes a defense position monster to be destroyed instantly, without losing life points. If Drillroid was capable of destroying Defence Wall, then their life points should have remained at 1700.