You can only choose one,you can only use white dragon form 1 time per long rest:

materialise white dragon spirit,he as her own turn but thats ou controlling them,he can use an action to use celestial beam,that is literally a celestial beam,that deals,1d10+3,or you can use an bonus action to materialise him,than he can use fisical attacks,but only deals,1d6+2.

use the colorfull forces on your attacks,if you are with half of your life or less ,you deal the double of the damage,if you are not you just deal 1d6+2