The Gather Specimens replacement effect is applied before any other replacement effects that would also modify how the creature enters. These are usually worded "as [this creature] enters" or "[this creature] enters with." For example, if your Gather Specimens has resolved, then the following things are true: -- If a creature with devour would enter under an opponent's control, you choose and sacrifice your creatures as it enters under your control. -- If Voice of All would enter under an opponent's control, you choose a color as it enters under your control. -- If Clone would enter under an opponent's control, you choose which creature it copies as it enters under your control. -- If a Wizard would enter under an opponent's control and that player controls Sage of Fables, the Wizard will not enter with a +1/+1 counter on it as it enters under your control. -- If a Wizard would enter under an opponent's control and you control Sage of Fables, the Wizard will enter with a +1/+1 counter on it as it enters under your control.