"wilier" in the adjective sense
1. crafty, cunning, dodgy, foxy, guileful, knavish, slick, sly, tricksy, tricky, wily
marked by skill in deception
"cunning men often pass for wise"
"deep political machinations"
"a foxy scheme"
"a slick evasive answer"
"sly as a fox"
"tricky Dick"
"a wily old attorney"
Source: WordNet® (An amazing lexical database of English)
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