Druidic blood spells use the life force of a sacrificed animal to create new life or heal and is one of the ways I have been thinking of to make druid magic different from clerics and magic users. It could be compared with Dark Sun defiling but druids wouldn't do that, even evil ones. The reason is simple- druids draw their power from nature and can be seen as those who worship it and those who use it. Even those who use the power to their own ends see that destruction of nature will only bring themselves to ruin.

So, druid blood magic is a method of transfering life energy from one place to another. If all life energy is the same, from that of humans to that of dragons and beholder, then monster hunting will become an important part of druidic life. Monsters that disrupt the natural world can be used as a resource to restore the flow. If you are planning on using this version, I suggest adding Sleep as a second or third level spell and a Greater Sleep spell at 6th (it affects five times as many creatures as the basic spell) to the druid list. It could also be used to create life from clay. Sculpt the desired creature and then use living blood to turn it into flesh or vegetation. Or use it to animate golems or other constructs. In this case I would use B/X type golems, those without the immunity to most spells. Constructs made of stone, wood, soil, water, sunlight, moonlight and ice are the most common but anything from the natural world is possible.

If life energy differs, then druids may avoid slaying monsters in the wilds unless it is unavoidable. They may capture them and contain the energy in stones or bodies of water and hope that the energy never escapes. The container will change over time, becoming more and more corrupted with the energy and physically change. It may even be a handy body for a golem, using monstrous energy against monsters. Druid magic should not only include Sleep and variants but Domination spells. The latter allow the casters to ensure the monsters obey them and make it easy to get said monsters to the container's location. If the energy can not be contained, then the druids may redirect monsters into wastelands or, rarely, cities so that their energies taint as little of the growing world as possible.

And then there is the druids that use natural death as a source of energy. Many gain the most power in fall as plants die back and the frosts kill off some animals. Others live in cities, at least for a time, and those who die from disease, old age and violence give the druid what they want. If it is at all possible, the storage of this energy would be in amulets druids wear at all times. If the energy can not be stored, the druid will have to find places where the dying congregate.

There are several spells that I would use with bloog magic beyond those in the article. Create Treant is like Changestaff but creates a permanent, intelligent creature. Destroy Undead I-IV (levels 4-7) use the life energy not only to kill increasingly powerful undead, but also to turn corporeal undead bodies into vegetation and incorporeal undead into healing energy and in both cases, remove the taint, if any, they caused. End Curse is a much more powerful version of Remove Curse as it is meant for locations rather than people and objects. It allows the Evil Forest to return to its precursed state. I wonder why druids didn't get Remove Curse in 1e?

Some questions that the GM will have to answer before using any version of blood magic: do plants have any significant amounts of life energy? do levels and hit points matter or is it based on size, constitution, species and/or intelligence? does including a sacrifice increase the power of existing spells? if so which spells can be affected and how*? can life energy be used to create new life? can it be used to alter existing life? and can it be used to revive the dead?

*Personally I would include Plant Growth, Animal Growth, Entangle and similar spells. Use of blood magic may even be helpful in Summon Insects and Insect Plague as the magic causes the insects to go through a form of mitosis (splitting into multiple adults, thus increasing the size of the swarm).