how 2 play venture?

ive been trying to play venture for about 3 days and i feel like i havent gotten anywhere. ill do the most insane flank known to man then try and hit an enemy sniper with ventures combo but be cancelled by an enemy support healing them 2hp, completely disengaging my ability to secure the kill. I also have this problem where if i hit the combo too early my drill attack sends them flying making me unable to do any damage with a melee attack, making me completely unable to secure the kill. I would look at guides but none of them address these glaring problems so I thought asking here would be a better idea.

is venture actually just useless? if so it might make sense why all of you are mentally unstable (including me x)

what do?