Renata's power is equal to your devotion to green. (Each in the mana costs of permanents you control counts toward your devotion to green.)
Each other creature you control enters with an additional +1/+1 counter on it.
Renata is a mono-green +1/+1 counters and go-wide commander that snowballs your board by giving every creature an extra counter on entry. You ramp aggressively, flood the field with creatures, pump them with counter synergies and anthems, then swarm or trample over opponents. Renata herself grows huge with green devotion and can wear pump or trample to act as a backup beater.
Free, passive value: every creature enters bigger with no setup required
Mono-green consistency with excellent ramp and few color screws
Synergizes with proliferate, doubling effects, and counter payoffs
Renata scales as a real threat thanks to green devotion
Cheap commander that's effective even when the deck is built around her cheaply
Mono-green means weak interaction and no real removal for problem permanents
Board wipes are devastating to a go-wide counters strategy
Renata only buffs other creatures, not herself directly via counters
Can be outpaced by faster combo decks
Lacks card advantage engines outside of creature-based draw
The premier finisher that turns a wide, counter-boosted board into lethal damage.
Prioritize counter-doublers (Hardened Scales, Branching Evolution, Doubling Season) and proliferate enablers to multiply Renata's passive, and add fast mana like Sol Ring and green dorks to deploy threats early. Tighten the curve with cheap, efficient creatures and pack multiple overrun finishers (Craterhoof Behemoth, Triumph of the Hordes) so a stalled board still wins. Add resilience with protection spells like Heroic Intervention and recursion to fight through inevitable board wipes.