I'm just saying it gets annoying when people just give you fan-boy answers.
im not giving a fan boy anwser but if the tyranids block the warpl. so nothing to do with the warp is possible then how can chaos do anything they cant even get into our dimension let alone try to take over the hive mind
I never said they could take over the Hive Mind. Because the Hive Mind isn't at everywhere at once. Well, it is, it is where the tyranids are, but it is weaker when less tyranids are about.
Chaos can't get into our dimension because they basically demons. Or, more accurately, demons are warp entities. Demons have to have a host and or sacrifice to enter reality, and even so they allotted a limited amount of time. A Horror might require ten sacrifices, a Changer of Ways a 1,000. So imagine the sheer amount of sacrifices you'd need to bring in Tzeentch? I would think it would be a pretty much insta-win for Chaos if even Slaanesh was brought in for while.