War chariot.

So umm there is a gladiator beast on the field, opponent summons BLS attacks the monster activates eff, chariot can be activated?

and is it the same with shura?

another situation, what if the GB is facedown?

You can only activate Gladiator Beast War Chariot if there is a face-up "Gladiator Beast" monster on your side of the field. If a monster is destroyed by battle, it is not longer treated as being face-up on the field. If you controlled more than 1 face-up "Gladiator Beast" monster and one of them was destroyed in battle by Black Luster Soldier - Envoy of the Beginning and the opponent chose to activate the effect of it, then you can activate Gladiator Beast War Chariot in response, but if you only had the 1 face-up "Gladiator Beast" monster, then no.

Actually, BLS active its effect after the GB is sent to graveyard, so Chariot cannot be actived.

BUT, if your opp use Red Dragon Archfiend and active its effect after damage calculation, GB still face-up at the time, so Chariot can be actived.

I'd like some confirmation on these answers as we have differing opinions and tbh I dunno

There both right harper.

If you control only 1 gb you cannot activate chariot because ur gb is in the grave whwn bls effect activates.but if you controal another one then you do have the requisition to activate chariot when bls effect activates.

actually red dragons effect is mandatory so you dont activate it, it activates itself. either way you can chain war chariot to it as long as you have a GB on the field.

and as long as you still have a GB on the field after the attack from BLS then you can negate because the effect activates and war chariot doesnt specify that the opponent must activate the effect. you are also able to activate war chariot because it is a counter trap and BLS 2nd eff activates in the damage step, which would stop most other cards.

so to answer your question, as long as you have a GB on the field after BLS first attack, then you can use war chariot