Complex sentence: Chisda was a great casuist ('Er.67a), his acute mind greatly enhanced the fame of Rav Huna's school at Sura, but his very acuteness indirectly caused a rupture between himself and Huna.
Split into simpler sentences: Chisda was a great casuist ('Er.67a), and his acute mind greatly enhanced the fame of Rav Huna's school at Sura. But his very acuteness indirectly caused a rupture between himself and Huna.