When upgrading Lavamancer fissures to tier 2 during battle, they immediately upgrade instead of having to wait the normal build time.
I think at release you didn't have to upgrade it at all, but then first patch after yeah they changed it to the current way. I kind of forgot about it as I haven't being using fissures much, but it still seems weird.
Wasn't sure if this was an intended choice for this tower, kind of like how the archer towers can be spam built. But since they approved it, I guess it is an oversight not a design choice .
Been like that since release