Abstract: We investigate the formation of intermediate mass black holes (IMBHs) through hierarchical mergers of stellar mass black holes (BHs), as well as in-cluster and ejected stellar-mass BH mergers in massive globular and nuclear star clusters using the semi-analytical cluster code cBHBd. We have incorporated probabilistic mass-function dependent BH-BH pairing, binary-single encounters and mass-ratio dependent prescription for energy absorption in hardening binaries in cBHBd. We find that IMBH with masses of O(2) – O(4) M⊙ can be formed solely through hierarchical mergers. Clusters with escape velocity of at least 400 km/s are the most efficient in forming high-mass IMBHs. The final IMBH spin is found to be 𝜒 ∼ 0.7 – 0.1, inversely related to its mass, a trend similar to supermassive BHs; which may point at supermassive BH formation through smaller IMBH mergers. We also find that eccentric double BH mergers are more frequent in the stellar-mass range such that metal rich, young, dense clusters can have up to 20% mergers with eccentricity ≥ 0.1 at 10 Hz and ∼2-9% of all in-cluster mergers can form at > 10 Hz, making eccentric and burst BH-BH observations a vivid possibility to current gravitational wave detectors. Although stellar-mass mergers dominate by sheer number, clusters of extreme mass (∼ 1𝑒8 M⊙ ) and density (∼ 1𝑒8 M⊙ pc−3) can have about half of all its BH-BH mergers with a primary mass of at-least 100 M⊙.