Core Items Buy in the order presented. All these items are really important. Only Imbue your Burrow because there's no point in Imbuing any other ability.
Additional Items - Ideal For Burrow Non-Core items that I always build because I think they pair extremely well with Mo's Burrow. Always build 7 or 8 Spirit Items. Buy whichever of these you want, but I usually go with Fortitude and either Armor. Shadow Weave could replace Lifestrike late-game. Build these any time in-between your Core Items. Buy Enduring Speed against Kelvin.