Best combos using spike growth?

[dnd2016]

I like thorn whip, d.whispers and fear, ( if they dont know its there), Thunder wave.

[Foxhound438]

repelling blast jumps to mind, have one character set up spikes behind the target and one repel them into the spikes. Pretty efficient, as it only requires a level 3 druid and level 3 warlock. This team can work flavorfully too, thanks to fey patrons.

Now that I mention it, I feel that these two would make a good NPC pair, in the right campaign.