This spell had two different effects, depending on the caster's target:
If dweomerflow was cast on a wizard or mage, it caused the next spell they cast to have no effect and rather flow into a prepared item, set as a magical receptacle. Examples of these included focal stones, crystal balls, artifacts or magical devices that required recharging. It created a resonating field between the caster and the item, allowing the magic to flow from one to the other.
If the spell was cast on an item, it allowed the caster to share charges or stored spells from that item to another, using their own body as a conduit. The caster was required to have physical contact between both items during this process.
A fountain of holy water, consecrated altar or similar divine site could store a dozen or so spells that had been accompanied by a casting of dweomerflow. They could then have been gradually released by someone of the same faith to which the site was sanctified. More powerful spells required a casting of abeyance in addition to dweomerflow.
Many holy sites scattered across Faerûn were well-protected by powerful offensive spells that were released if they were intruded upon by the faithless. This magic was often stored within a holy symbol that was doubtlessly present at the divine location. To bypass these spell effects, a cold iron tool could be used to remove the symbol, circumventing the effects of dweomerflow.