Tappers are a bit outdated now and 2 mana is a little too much to activate, so I dont think Coeurl will be too good
If it shares a creature type with this creature, you may reveal it
Youll get to fix your next draw and possibly draw an extra card, and theres never an actual risk that Gollum dies to a blocker
Whispers in the Well
In my opinion, the strongest things you can do in Mono Red are: "Glass cannon" decks that either quickly pop off and win before opponents can stabilize, like Storm, Krenko, Purphoros, Slicer Crushing nonbasic lands, aka defeating a large chunk of players with a single Blood Moon The problem with these two strengths is that they aren't always the right pick for casual tables
Last but not least, Crystalize is a powerful unique ability, making it even more certain that you can target and destroy unwanted Evasive characters before they cause too much damage