It was an almost relieved cloud of frost that was expelled from the Archlich's jaw upon hearing that the fussy undead dragon guarding his quarters might actually be placated, as he was getting tired of having to close the gates every time the gigantic wyrm decided to throw some sort of fit. A clattering of teeth was the only response to the challenging edge to the Plaguelord's words, however, as the floating wraith did not, at this moment, wish to go into full detail his superior grasp on necromancy compared to the San'layn's. An arrogant stance? Perhaps, but he was too pleased to have company to speak of it aloud, and risk squandering the potential for companionship.
There were indeed a few glowing shards strewn across the wooden surface, and the Lich himself was currently slightly more seafoam green than the normal frosty blue you could generally find swirling within his ribcage.
"oH, pLEASe dO reFRAiN, I hAVE lOsT aN eMBARRasSing nUMBEr oF DeATH kNIGHts tO MAEXxna'S wRAth, aND iF I alLOWed hER sPAWN tO bE deVOUreD So EaSilY, I'd eND uP bLAMinG yOU fOR thE loSSes."
The glowing specter drifted idly over to a nearby tome, holding it aloft and peering at the contents, gleaning the information with willpower alone. His free hand held one of the foreign gems pilfered from an alternate universe, which began to shine fiercely, almost blindingly.
The Archlich whispered an ancient language, coursing with hisses, clicks and such sharp consonants it sounded much more akin to an enraged slew of expletives than an incantation, before the Apexis crystal finally shattered in his skeletal palm. The pulsing energy flickered and pulsed in Kel'Thuzad's grip, and was then purposefully hurled directly into the Plaguelord's abdomen.
The Lord of Naxxramas was formerly an Archmage, an enhancer, a master enchanter and able to wield the Arcane with such prowess even the Elven Magisters called upon him to share his knowledge. He was a Necromancer, he would raise the dead, control them and empower them. He was an advisor and a leader, often called upon to rally the troops and give proper motivation.
As such, it was only proper for him to augment the capabilities of those around him, to boost his soldiers and lieutenants simply by being in his proximity, yes, these crystals were a power source, and being the powerful wizard he was, it was quite easy to share the raw energy with those who were more likely to go out and fight on his behalf, transformed into something they could utilize.
If the fallen Highborne allowed contact, the spell would temporarily augment the potency of each drop of blood within the Scourge commander's body, boost siphoning capabilities, and allow regeneration even to dead flesh.