PSA Don't build Luden's echo as a support.
Its not good its bad. Here are the reasons you build Luden's
- mana 2.ap
- it helps with weave clear. Now you don't need the mana as a support since the support item gives enough unless your like taric or sona. The passive does nothing as support since your not going to have the ap to do damage with it and you don't need the weave clear. The ap is nice but other ap items give similar ap like Rylai's and has a passive that helps your team, and items like liandry's do more damage since most damage supports can make use out of the passive.
Like all your doing by buying it is buying 90 ap nothing else.

and so on... ) - your efficiency comes from harassing the enemy with abilities. As long as you're doing a good job at pressuring the enemy - without doing CS both lane (cause then you're trolling your adc) - you can still be a good support. While latter on you can also play as a 2nd APC.