The main issue with this achievement is claiming a boss tile, as you may be required to fight 2 tiers of the boss rather than 1.
Combined with the limited tower selection, it can be quite tough - so I'd recommend you just do a 1 tier tile (the tiers required are on the box that pops up when ya select "play").
Getting within range of one can be annoying too, but it's not all that hard most of the time.