Advanced Golemancy is the research you need to get an Iron Golem Guardian.
For more information, see Golem.
"You now consider yourself well-versed in the art of Golemancy. It is time to expand their capabilities beyond that of simple workers: There is potential to turn them into warriors as well.
You have managed to refine the basic golem body into something sturdier and more agile. The result is a construct that should be quick and strong enough to enter combat. These golems also repair their damage twice as fast as worker golems.
Your first practical application of this knowledge is the creation of a Iron Golem Guardian. This golem, when placed, will guard an area from intrusion and attack any monsters that dare enter it. Smart versions of this golem can be assigned a wider variety of targets (including creepers, whose blasts they will attempt to avoid). Unfortunately these golems are limited to melee combat only."
Research available after The Theory of Everything.
You can craft it in a Infusion Altar.