Heals and shields are 5% stronger and increased by an additional 10% on targets below 40% health.
Offense
+5 AD or 9 AP
Flex
+5 AD or 9 AP
Defense
+6 Armor or 8 MR (match-up)
WhyConqueror
Morde excels in extended fights where you're able to ramp your damage over time with your passive. Conqueror empowers that but dealing bonus true damage with every passive tick.
WhyTriumph
Triumph synergizes well with Morde's [R] allowing you to come out the other side healthy enough to continue fighting.
WhyLegend: Tenacity
Morde's biggest weakness is his lack of mobility and ability to be kited. You need to stick to your target to deal damage and Tenacity will go a long way in doing so.
WhyCoup De Grace
Coup De Grace is the defacto damage amp choice, especially for Morde as you will be building a few health items.
WhySecond Wind
Second Wind is great for extended fights/trades allowing you to sustain health rapidly over time when combined with Doran's shield.
WhyRevitalize
Revitalize synergizes extremely well with Morde's [W], empowering both the shield and heal portions.