ENPP is an algorithm that reduces permutation times via pruning of insignificant markers, when the markers satisfy pre-defined pruning conditions.
Consequently, it can obtain significant markers in a feasible time, even for data sets with large numbers of features such as GWAS SNP data sets.
Detailed algorithm is described in the below original article, "Enhanced Permutation Tests via Multiple Pruning, Front Genet. 2020 Jun 25;11:509. doi: 10.3389/fgene.2020.00509."