guard dog needed for base as towers have been replaced with laser pointers

My team are behind but with the late game gods on our side (vayne, jax) I attempted to motivate the crumbling troops "just defend the base guys we can win easy late game" Suddenly the enemy team appeared at the first inhibitor tower and we rushed towards it as 5 to hold back the attackers while staying under the safety of the laser tower. Just as the minion wave is cleared the enemy team attempts to dive. Ha i think to myself we will surely win this fight as we have the laser tower on our side. As the fight continues i notice that the beam directed towards the enemy tank does not seem to be doing any fucking damage. We were pushed back under the nexus towers having lost the middle inhibitor and 2 friendly champions and as the next minion wave approached we prepared for our final stand. Once again the wave was cleared with ziggs powerful bombs but it did not matter as the tank who still had over 3 quarters life remaining suddenly dived the 2 nexus towers. Surely this will prove their undoing but to my amazement the 2 little beams focused on the tank and still did no fucking damage and so we were aced losing nexus and the battle. Our late game team had not made it to the late game because there was no way to defend the towers against these tanks even with great waveclear as the towers were proved to be too fucking useless. This is the reason i think riot should add a huge fucking guard dog that can be deployed straight from the nexus to swallow up these annoying fucking tanks in a single bite.