the chance of rare drop in dark tower's boss

[Coburg]

so im just wondering,is the chance of getting rare from dark tower's boss are the same from a normal boss,bcoz dark tower only costs us 12 energy and with +1% luck orb,i would just do dark tower

[Zurga]

As far as I know, yes the chances on any boss are the same.
The frequency of rare cards depends directly on the level of the boss.
Same rules for any boss.