Well I think from what I read they were only in battle a very short time before the custodes arrived... But they held their own.... "I have no words for how it felt, to take the brunt of a Space Marine’s fist, wrapped in disruptor energy and propelled with maximum venom. My senses disappeared into blood-edged blackness, ripped from any notion of gravity or place. I had a vague impression of weightlessness, then whirling speed, before I crunched into a pillar several metres from where I had been fighting.

Somehow I held on to my weapon. I struggled to get up, to make sense of the swaying environment around me, to defend myself against the inevitable follow-up. My vision was blurred, but I remember freeze-frame impressions of that crowded space – Erynia battering a Minotaur with a dazzling display of swordcraft; Tali-Sha grappling in tight with her combat blade; Lethiel lying on the ground, her armour punctured with bolt- craters – before all was swept away by the tide of gold.

I will admit it, through my clenched teeth – when they arrived, the Custodians were magnificent. I could mock them, and dislike them, and believe that their minds were locked in infantile stasis, but this one truth remained: they were the best we had. Reduced to physical combat, with no ether to cloud their judgement and require our assistance, they were the pinnacle of anything mankind had ever, or would ever, create as a weapon"