The time-stream is the normal passage or flow of time and its historical developments, within a given dimension of reality. Elder gods are all-powerful beings that exist outside this reality within their own dimensional plane. As they are not subject to the traditional rules of time and space, they are able to view the time-stream in its totality. This allows them to observe all events from past to future at once as would a spectator. These gods are able to enter the stream from their dimension onto the mortal plane. However, as time operates similarly to the flow of water, the current of the stream can ebb and flow in both direction. This makes their control over where they enter is extremely limited. They can aim for the middle ages and end up in the 51st century, as they are subject to the volatile tide of the stream at that point. The solution to this would be a physical manifestation of themselves called an avatar that can serve as an anchor to a specific point in the stream. These avatars would function as "landing zones" that would operate as a beacon, guiding the deity through the rough flow of the stream, similar to the purpose of lighting houses serving as beacons to ships on the open sea. To accomplish this, I would need help from mortals on the other side to build this avatar on their behalf, and must find some way to communicate with lowly mortals to carry out its desires.
The problem is that the minds of humans are frustratingly fragile, while the mind of a god is vast and incomprehensible. Any human that touches the mind of a god will go irrevocably insane. Even cults devoted to worshiping it are not immune to this fact, as they may be subject to misinterpreting the my will. This often devolves into human sacrifices and goals of ending the world in order to bring about their my return. Written texts are also not an option, as this can lead to the same problem. A god can clearly and plainly dictate its intentions (Thou shalt build an avatar of thy lord, and not kill each other in the process of thy making it) and those same followers would spend decades debating and interpreting the meaning of their words and their deeper meanings. This would also devolve into schisms of faith as different factions fight over minuscule differences, leading to religious wars. (You humans are weird that way I guess).
How can I make known my actual will and guide the hands of my followers from a higher dimension without directly communicating with them?