I have a Master Biomancer in play which power is 2. I play Elvish Champion. How many counters does it get?
This is clearly rule 614.12, which unfortunately is not clear at all.

614.12 Some replacement effects modify how a permanent enters the battlefield. (See rules 614.1c–d.) Such effects may come from the permanent itself if they affect only that permanent (as opposed to a general subset of permanents that includes it). They may also come from other sources. To determine which replacement effects apply and how they apply, check the characteristics of the permanent as it would exist on the battlefield, taking into account replacement effects that have already modified how it enters the battlefield (see rule 616.1), continuous effects generated by the resolution of spells or abilities that changed the permanent’s characteristics on the stack (see rule 400.7a), and continuous effects from the permanent’s own static abilities, but ignoring continuous effects from any other source that would affect it.

Do I read this selected part right when I conclude that Champion will boost the Biomancera power, gaining itself a third counter?
…check the characteristics of the permanent as it would exist on the battlefield, taking into account… continuous effects from the permanent’s own static abilities

Hi,

The key word is “it” in the phrase "characteristics of the permanent as it would exist". We're only looking at what the Champion would look like once it's on the battlefield, not how other objects would exist with it once that card is on the battlefield. Since we're just looking at how the Champion would look, not how other permanents would look with the Champion on the battlefield, the Champion will only enter with two +1/+1 counters, not three.

Nathan Long
Magic Rules NetRep