Ember Beast suggests you don't need much drawback to get a 3/4 for 3 mana in red. The extra coloured mana in the cost probably makes up for the tribal protection, so I'd say this would be fine at 3/4.
"Attack each turn" is much less of a drawback than "can't do it alone", especially on a 4-toughness critter. Besides, you can have a 3/2 for with upsides already (e.g. Crossway Vampire, Archetype of Aggression).
For Challenge # 023 in a cycle with Grave Bramble
Ember Beast suggests you don't need much drawback to get a 3/4 for 3 mana in red. The extra coloured mana in the cost probably makes up for the tribal protection, so I'd say this would be fine at 3/4.
"Attack each turn" is much less of a drawback than "can't do it alone", especially on a 4-toughness critter. Besides, you can have a 3/2 for
with upsides already (e.g. Crossway Vampire, Archetype of Aggression).