I need encounter advice for my level 4 party of 2

[Dox of the ParaDox twins]

Hi. I'm planning out a session for my group this Tuesday and I'm stuck. I need encounter ideas that would be interesting and fun for my players.

Context: there are 2 of them. One is a malefex (think a mesmerist basically) and the other is a dex magus. Neither are horribly optimized, but they also both have roughly 1.5 times the gold/items they should have. They are currently in a big ass tower/dungeon (think stone tower from zelda) and I'm really struggling to think of encounters for them. Do y'all have any cool ideas I could steal?

Thanks

-Dox

[Firebug]

Per encounter design, the APL is 3 (If your group contains three or fewer players, subtract one from their average level). So XP budget for encounters should be around 600 for easy, 800 for average, 1200 for challenging, 1600 for hard, and 2400 for epic.
Since you have a tower...

How about a locked door with several elemental symbols on it. Several columns(Caryatid Column/Animated Object(medium)) around the room when activated(probably individually to make it easier) and destroyed summons a Mephit or Medium Elemental of various types (again individually). If you figure each set (column+summon) as an encounter since they trigger the encounter by activating the column, they should fall into APL+2ish hard encounters. Maybe even APL+1 since there is only one monster at a time.
Probably do something like the construct breaks out of the pillar when activated to avoid them always getting the surprise round.
Otyugh as a garbage disposal.
A nest of Dweomercat Cubs taking shelter in the larder with the mother ambushing the party the next day.
A squad of Atomies, Grigs and Mites plotting the destruction of the local town.

[Dox of the ParaDox twins]

Ooh. Very cool. I love the column idea.

Thanks

-Dox