Manipulating Somones dreams

A while ago, my friend got high off weed brownies so much he travel to a place and met a spirit he thought was GOD. GOD told him “your training begins now”, whatever that means. Is there any spirit powerful enough for me to summon to give my friend a powerful psychedelic experience so real he believes it exists? Is there a spirit that can take a different form and show up in a dream/drug trip to make him believe GOD is telling him whatever I want the spirit to say? If there is could you give me its sigil?

I believe it would be possible, but why not soul travel to the person while they sleep and implant your thoughts and desires into their mind, so as they believe such thoughts and desires are their own? I guess it would depend on whom you were seeking to influence. Would “I believe God has comanded me to…” hold more sway than “I truly desire to…”?