3on3 Twisted Treeline

So I was playing 3on3, before that I was assure that there's a new ap item called "Luden's Echo" Which is built from Needlessly Large Rod(1600g) and Aether Wisp(850g) So I knew that is gonna be pretty interesting item. So right now I was sure like it's for 5on5 only. But then I played few games got the same opponent twice, who built "Luden's Echo" on 3on3 Twisted Treelie which you should not be able to. Since Needlessly Large Rod cant be purchased on 3on3. So if you try to build it by piece by piece it wont let you buy The NLRod but you can buy the AWisp.