* Grapha's effect is not a "card effect": Grapha's effect is a continuous effect that automatically triggers when a monster is destroyed, not a card effect that is activated.
* War Chariot negates "card effects": Gladiator Beast War Chariot's effect only negates the activation of a card effect, not continuous effects like Grapha's.
Here's a breakdown of the situation:
1. Grapha's effect: When a monster is destroyed, Grapha's effect automatically triggers, destroying another monster. This is a continuous effect, not an activated effect.
2. War Chariot's effect: Gladiator Beast War Chariot negates the activation of a "card effect". This means it can only negate effects that are activated from the hand, field, or graveyard, not continuous effects.
Therefore, you cannot use Gladiator Beast War Chariot to stop Grapha from destroying another monster. You would need a different card that can negate or prevent continuous effects to counter Grapha.
Note: Some cards can negate continuous effects, but they are not as commonly used as cards that negate card effects.