Jogging my memory. The Heal Check in Dreamwalker was largely performing the float/bubble mechanic, as no amount of gear let you bypass the huge healing buff you received from said mechanic. You may collect the orbs periodically, but if memory serves, it was possible to chain the duration so that it never fell off, and kept it stacking to stupid levels. (Which falls under the 'handling a specific mechanic' part.)
Though you are right. Karazhan had one, SSC, TK had them, BC and Sunwell. Brutallus was just a straight up check all around. (Tank, healer, and DPS check in one).