Loop Assembly has been developed in the Haseloff Lab by Bernardo Pollak and Fernarn Federici, is an efficient and simple type IIS method that uses BsaI and SapI as type IIS enzymes, and two sets of 4 plasmids for cloning from one level into the next. This is the method being used in Marchantia to assemble L1 and L2 constructs. Paper on Loop available in bioRxiv. More details here.
Also, in the lab we are working on Loop2.0, with same framework as Loop but different set of cloning vectors. More details here.