Here's what rhymes with substantify.
high thy vi hi shy sigh defy fi hy thigh vie psi hai cy fy sy thei phi by my why die lie y buy fly sky deny guy tie bi bye chi dye nigh pi pie spy thai dei fry ly quae rye sly ty wir awry lye mai muy nai wry belie kai lai luy mei tai wai sty stye turfy slier dandify dry try cry justify rely modify notify ply quantify underlie amplify pry standby tri trie beautify decry pri termini typify descry edify mortify bonsai deify spry stultify gentrify banzais yuppify apply supply identify reply thereby imply nearby whereby hereby testify butterfly certify fortify nullify pacify ratify pupae terrify untie codify dignify mollify overlie ramify vilify aquae mystify ossify stratify triply ultrahigh vivify amebae blowfly stupefy lanai scurfy barfly mummify prettify shanghai beatify ripply speechify overbuy syllabify occupy satisfy stimuli comply nuclei specify alkali signify simplify verify goodbye gratify purify alibi magnify rectify samurai unify solidify amoebae liquefy objectify personify acidify demystify detoxify firefly retry calcify horrify misapply petrify liquify overfly versify hyperbolae vitrify drachmai refortify clarify multiply qualify classify glorify intensify alveoli diversify falsify indemnify lullaby crucify oversimplify resupply dragonfly emulsify reunify revivify dissatisfy scarify declassify misidentify solemnify exemplify disqualify oversupply electrify preoccupy reclassify cumuli transmogrify