Jackal+Joon specials works on either side of the board, though the odds that the AI will choose the same target are too low.
What we think is true is that the slash attack of a defender is colorless. Example: defending Frida casts, then the next turn gets her slash attack. The slash attack hits for normal damage.
There is no synergy between Jackal and Ursena. Jackal’s special makes its target more susceptible to holy damage. Ursena’s attack does more damage against holy foes.