If i ever had russell, here is how i qould use it (tips maybe for someone who has it)

If i ever get russell (unlikely) my use on him would depend on 3 things

Heal spas-depending on how many heal spas the map has, he could be incredibly good on maps without spas, but can be not as great on maps with maybe 2 spas

Enemies race-depending on what race and how much of that race the enemy is using, he can be demonic on an enemy with mostly dimensionals and undeads, or basically useless on an enemy whos using mostly mechs

And most importantly

Amount of enemies keys-depending on how many keys the player has left, means russell might be a lot better for late game, because if the player has little to no keys left, it means they cant spawn any healers, allowing russells poison to take effect on enemies without any cure

These are what i think are the best tips and tricks for anyone who has russell and cant find any use for him