All runes are legit.
Some gameplay tips:
Monsters that have the highest drop rate for Cham rune
Monster Difficulty Drop Rate
Council Member Hell 0.00002485
Ismail Vilehand Hell 0.00002485
Geleb Flamefinger Hell 0.00002485
Toorc Icefist Hell 0.00002485
Bremm Sparkfist Hell 0.00002485
Wyand Voidbringer Hell 0.00002485
So now we know where to go to farm Cham rune - the last few acts of Act 3, especially where the unique high council members are.