Malzahar & Rell Synergy
Malzahar Mid and Rell Support win 56.2% of 2,154 Low Elo games together, +2.1 points vs expected, 2-patch window 26.19-26.20.
Researched on LoL patch 26.20. Tips are written to hold at any rank; stats come from Low Elo ranked games up to patch 26.20.
Why this duo works
Rell's engage and movement-speed link can bring Malzahar into range and hold enemies in place long enough for his E/W damage and point-and-click R to land. The pair works best when they coordinate the target and Malzahar is close enough to follow the engage.
Playing the duo
Rell can start with a knockup and pull multiple enemies with W/R, while Malzahar adds a damage-over-time mark and single-target suppression(R) to keep one priority target locked down for the team's follow-up.
How to play as Malzahar
Stay close enough to follow Rell's engage. Let her W/R place the target, then use E/W and Nether Grasp(R) on the priority target so the team can focus it.
How to play as Rell
Use Full Tilt(E) to help Malzahar reach the fight, and commit with W/R when he is in range to follow. If he is too far away or R is down, keep your engage for peel or a later opening instead of diving alone.
Sources
These notes come from r/supportlol, checked against the champions' abilities.