thanks for sharing your info about Ghelamco's projects with us, but I see that some stuff needs to be explained:
1. A project discussed in this thread is called Prosta Office Centre (a word "Prosta" comes from a name of a street, and means "straight") which was (and probably is) planned to comprise three phases of about 20k sq m each and look like this:
POC was designed by Montois Partners Architects cooperating with Belgian architect of Polish origin Ludwik Konior, who continued the work in his own firm. The building on the left (phase 1 of POC, or just POC) has already been built. The remaining phases are to occupy quite small plot between phase 1 and big roundabout on a crossing of Prosta Street and Towarowa ("Merchandise") Street
2. "Prosta Tower" which you show can be seen on the right side of the above rendering and was/is (?) planned as phase 2 or 3 of POC, being 20-story office tower. The tower's rendering can be found on Konior and Partners web-page:
with a misleading name "Prosta Towara", coming not from "Prosta Tower", but wrongly spelled "Prosta Towarowa" (which are the names of the streets). There is Prosta Tower project, but it refers to completely different, although nearby, residential tower developed by Marvipol and designed by Polish firm APAKA. We don't know how this Ghelamco tower will be called (whether it's gonna be POC or something else), but for sure it won't be Prosta Tower. As for its height, we know that a few months ago Ghelamco applied to Warsaw authorities for a permit for 94 meters high building, which could be that tower by Konior or something new and a bit taller (and hopefully with better design!) since Konior's 20-story building rather wouldn't reach 94 m. Of course they could have changed their plans in the meantime and decided to build much higher building, but on the plot there is surely no room for "many" high towers mentioned by you.
3. Ghelamco has recently acquired a new plot for high-rise developments in a vicinity of POC, at Towarowa Street, with old printing-house to be demolished, and we know that they plan to build two 35-story office towers and two residential towers of 31 and 20 stories (plus a few low-rises) and that the complex is to be designed by Jaspers-Eyers and Partners. You can see locations of those projects on a plan (by SoboleuS):
where "7" is POC tower (your "Prosta Tower"), "15" - four new towers of Ghelamco (an exact name of this project hasn't been announced yet) and "6" - real Prosta Tower by Marvipol and APAKA. Probably you mean that project number 15, at the printing-house plot. We could figure it out if your info was more detailed or if you posted scanned rendering. If you meant the next phase of POC - we would be very happy if it really was planned to be higher and/or designed by someone more creative than Ludwik Konior.