As Kae, place all players under the effect of Blazing!.
They don't have to be from the same card, from the same turn, or even from the same player -- the effect simply needs to be active. When this happens, all Kae players on the map get the achievement. This is best done on smaller maps, particularly Practice Field, but once the stars align it's really easy to pull off. Try not to worry about it too much: just hold on to one of Kae's Hyper cards, and within a few games, the chance will arrive soon enough.
However, one good way to easily achieve this would be to play on Farm and stand in the very centre of the map while everyone else is there. The centre square of the map reaches across the entire centre of it. So it's a very good place to stand to get this achievement easily. You can either get friends to help you with it, or you can use computer players as sometimes the computers get confused on this map and continue going around the centre of it.