Whenever another creature you control enters, you may pay . When you do, that creature deals damage equal to its power to target creature.
Partner (You can have two commanders if both have partner.)
Halana turns every creature you flicker, recast, or generate into a removal spell, pinging down opposing creatures for their power on entry. You build a green creature midrange/value board, flood ETBs to clear blockers and threats, then close with combat or partner synergies. With Partner you pair her with a complementary color (often Alena, Kessig Trapper) to ramp out fatties whose huge power makes the trigger lethal removal.
Repeatable, color-light creature removal that doubles as board control
Excellent with blink, recursion, and token strategies that flood ETB triggers
Reach plus removal makes her a strong defensive anchor and fight-deck enabler
Partner lets you expand into a second color for more power and flexibility
Mono-green alone struggles with non-creature threats, fliers en masse, and enchantments
The tax per trigger is mana-intensive and slows you down
Effect requires creatures to enter, so wraths and creature removal blunt the engine
Low individual card advantage without a dedicated value engine
Doubles creature ETBs, though note Halana's reflexive trigger still requires paying each time.
Lean into a reliable blink/recursion engine (Conjurer's Closet, Temur Sabertooth, Eternal Witness) and high-power ETB creatures so each trigger is both card advantage and lethal removal. Add ramp like Cultivate, Sol Ring, and mana dorks to offset the tax, and commit to the Alena partner for a second color that opens better removal, draw, and finishers. Top-end Craterhoof or a counters package gives you a clean win once the board is stabilized.
Legendary Creature — Human Archer Ranger
. When you do, that creature deals damage equal to its power to target creature.