In the last Soulkeep AMA with DC by 
This is the stats after upgrading both options once each, speed option then damage option. Then I sold it back and did it again.
Here is the same options bought, but I chose damage upgrade and then speed upgrade this time.
Clearly something isn't right somewhere there.
Additionally while people are looking, I seriously have to ask if the Ivory Tower is bugged? This is working as it says it should but the first range upgrade option seems wrong to me. The Ivory Tower's opposite, the Dome of the Defiled has an initial upgrade option of 60 mana for a boost of 120%, over doubling the range. Meanwhile the Ivory Tower has an initial upgrade option of 100 mana for a boost of 13%! That's not a visual bug on the info pop-up. Paying the cost and clicking on the tower to see its new range shows its barely moved. I seriously think someone accidently dropped a 0 off the 13% and it was meant to be 130%. I think every other tower with a range upgrade option has a similarly much longer initial boost percentage. Many even upgrade more than 13% on each of multiple range upgrades available. Is it really working as intended here?