Maintenance for the week of January 19:
• PC/Mac: No maintenance – January 19
• NA megaservers for patch maintenance – January 21, 4:00AM EST (9:00 UTC) - 10:00AM EST (15:00 UTC)
• EU megaservers for patch maintenance – January 21, 9:00 UTC (4:00AM EST) - 15:00 UTC (10:00AM EST)
It's 6% increased block mitigation, block mitigation starts at 50%, so you are getting a 6% increase to that 50%: 1.06x50=53. This is why you will need 80% increased block mitigation to reach the cap of 90% damage blocked.