Te Samadhav upasarga vyutthane siddhayah.
Te = they; Samadhau = in Samadhi; Upasarga = obstacles; Vyutthane = in the state of out-turned-ness; siddhayah = powers.
They are obstacles in the way of Samadhi and power when the mind is outward-turned.
Various siddhis that a yogi acquires during his sadhana are just landmarks of progress. Trying to use them makes the mind extrovert, which is opposite to the yogi ideal of diving deep within one's consciousness through Samadhi. That is why all the great masters have warned against the use or exhibition of these siddhis or powers.
Once a man comes to the great master Sri Ramakrishna from across the river walking over the water and tells how he spent many years to acquire this power. Those days the charges to ferry across a passenger were four annas (twenty-five paise). So, Sri Ramakrishna exclaims, "Oh, you spent so many years just to get a power worth four annas!"
Thus, though the exhibition of siddhis is condemned, an Adept (a master) who has wisdom not to misuse these siddhis, has to acquire them as explained byI. K. Taimini: Perfection means and includes the power to control all the phenomena of all the planes on which consciousness functions and so the phenomena of all the planes on which consciousness functions and so the Perfect Man has not only to have direct knowledge of Reality but also knowledge and mastery of all planes on which his consciousness functions. That is why all the Siddhis have to be acquired at one stage or another before the stage of Perfection is reached.