Spirit of the Ancient Golem on Mundo?
Ever since season 3 the first major item any jungler would get was Spirit of the Ancient Golem. I understand that Dr. Mundo does not need mana regen but I feel that if I don't get Spirit my clear time would be reduced. On the other hand, there would be other items which would be more beneficial to him late game like, say, Atma's Impaler.
So, should I ignore the Spirit or stay with it?
The 500 health from Spirit of the Ancient Golem is as effective as any item short of Warmog's Armour, Frozen Mallet or a Rod of Ages. It also grants Tenacity, CDR, and Minion/Monster damage. This is not an item you should relinquish lightly on a HP-stacking jungle tank like Dr. Mundo.
Atma's will provide a bit more defense from physical attacks, and increased damage to champions, but will synergize much less well with Mundo's passive and Masochism. It also won't provide Tenacity, which combines with Burning Agony to render most CC ineffective against Mundo, nor Cooldown Reduction, which helps Cleaver spam, and brings Masochism into play more often.
In all honesty, you would ideally build both of these items, as Atma's works very well with Mundo's health-stacking playstyle, but Spirit of the Ancient Golem provides more utility, especially in the early-midgame