Mastery Rank 19 test walkthrough (Easier than you think)
(The number of enemy is 12, be sure to check before detroying the orbs)
For Warframe i chose Gauss because of his high sprint speed (1.4) but you can pick any Warframes you want.
As for melee weapon for this test "Skiajati" is your best choice, with its "unique ability to turn its user invisible on finisher attacks" you can reset the invisible status everytime you kill enemy with finisher.