Durkwood Tracker

{1}{G}, {T}: If Durkwood Tracker is on the battlefield, it deals damage equal to its power to target attacking creature. That creature deals damage equal to its power to Durkwood Tracker.

Volrath, the Shapestealer

At the beginning of combat on your turn, put a -1/-1 counter on up to one target creature.
{1}: Until your next turn, Volrath, the Shapestealer becomes a copy of target creature with a counter on it, except it's 7/5 and it has this ability.

Gemini Engine

Whenever Gemini Engine attacks, create a colorless Construct artifact creature token named Twin that's attacking. Its power is equal to Gemini Engine's power and its toughness is equal to Gemini Engine's toughness. Sacrifice the token at end of combat.

Marwyn, the Nurturer

Whenever another Elf you control enters, put a +1/+1 counter on Marwyn, the Nurturer.
{T}: Add an amount of {G} equal to Marwyn's power.

Tracker

{G}{G}, {T}: Tracker deals damage equal to its power to target creature. That creature deals damage equal to its power to Tracker.

Unliving Psychopath

{B}: Unliving Psychopath gets +1/-1 until end of turn.
{B}, {T}: Destroy target creature with power less than Unliving Psychopath's power.

Viridian Joiner

{T}: Add an amount of {G} equal to Viridian Joiner's power.

Marionette Master

Fabricate 3 (When this creature enters, put three +1/+1 counters on it or create three 1/1 colorless Servo artifact creature tokens.)
Whenever an artifact you control is put into a graveyard from the battlefield, target opponent loses life equal to Marionette Master's power.

Master Biomancer

Each other creature you control enters with a number of additional +1/+1 counters on it equal to Master Biomancer's power and as a Mutant in addition to its other types.

Dragon-Scarred Bear

Formidable — {1}{G}: Regenerate Dragon-Scarred Bear. Activate only if creatures you control have total power 8 or greater.