A lot of players do not know of, or are confused by how Imbue works because the tooltip lacks information on the power.
Imbue gives crit and severity based on the players health % at time of activation. It starts of at 12% crit and severity and caps out at 30% crit and severity. This information is nowhere to be be found in the mouse-over or the advanced tooltip of the power.
This information is important to understand how to use the power most effectively. Please add to tooltip.