Impossible fight mechanics

Looks like some boss mechanics require you to do things incompatible with combat mechanics, unless it is intended so interrupting player is only auto attacking, not using any abilities in anticipation for interrupt, though I don't believe this is the case.

Video for reference: http://youtu.be/40a_cnDQKeE

Time: 2013 09 15 around 21:42 pm GMT 0

Frequency:
too often

World name:
Cerberus

Character name:
Soul Pierce

Class/Level:
Bard 50

Party or solo:
Full Party

Area and coordinates:
Coerthas->Coerthas Central Highlands X31 Y7

Steps:
1. Use any ability and almost at the same time dhrome chimera start castin Ram's Voice
2. Try to interrupt with blunt arrow, but blunt arrow not going off (despite not being on cooldown and not affected by GCD) due to other skill animation still playing
3. Ram's Voice cast is finished before you have a chance to use Blunt Arrow - therefore a wipe.

Connection Specs
- Type of internet connection/provider: TEO
- Modem maker/model number: TP-Link TL-WR1043ND

PC Specs
-=-=-=-=- System Information -=-=-=-=-
Time of this report: 9/10/2013, 12:00:22

Operating System: Windows 8 Enterprise 64-bit (6.2, Build 9200) (9200.win8_gdr.130531-1504)
Language: Lithuanian (Regional Setting: Lithuanian)
System Manufacturer: System manufacturer
System Model: System Product Name
BIOS: BIOS Date: 02/24/10 14:02:48 Ver: 08.00.15
Processor: Intel(R) Core(TM) i7 CPU 920 @ 2.67GHz (8 CPUs), ~2.7GHz
Memory: 6144MB RAM
Available OS Memory: 6136MB RAM
Page File: 5429MB used, 1665MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.02.9200.16384 64bit Unicode

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Browser Information
- Name and version of the browser currently in-use: IE 10
- Internet Explorer Version: IE 10