Or search: crusader, reformer, reformist
2 Syllables: SU
bounded, bounden, fountain, mountain, mounted, ploughman, rounded, townsman, townsmen
3 Syllables: USU
accountant, compounded, endowment, expounded, pronouncement, propounded, surrounded

Found 16 words across 2 groupings. Skipped 6 excess words of a similar stem.