Firstly I read your effect of that card and it says that you can reuse one ability which is already been played and it will double its power but I don't think doubling its power means it will double its effect so that means you can only send one bakugan so....
Hydragon:700G Chronogian and pyreon and slight:400+500=900G
Now I will play my turn, Gate Card Open! Darkus Field! And Ability Activate! Phantom Blast! Also Fusion Ability Activate! Ultimate Phantom Blast! Effects:-1)Darkus Field increases Darkus bakugan power by 500G 2)Phantom blast increases my bakugan power by 100G for each card played by me in this round where as it decreases your bakugan power by 100G for each card played by me in this round. 3)Ultimate Phantom Blast increases my bakugan power level by 100G each turn and decreases your bakugan power level by 200G.
Hydragon:700+500+400+100=1700G Chronogian and pyreon and slight:900-400-200=300G (If you are wondering why 400G are decreased by your bakugan and increased in my bakugan then thats because I have played 4 cards in total in previous turns so by phantom blast ability your bakugan loses 400G and mine gains 400G)