This message applies not to people who are experienced at Demigod but rarely play Regulus, but rather new players that decide to use Regulus.
I just played a 2v2 game that was Oak(me) & Reg vs. Oak & TB. I used the "assassin" Oak build, and in my experience, having a Regulus ally with this build is very effective. Pentinence + me chasing/whalloping target + snipe can basically guarantee kills early on, even if the opponent has support (I might die in the process, but only at the earliest levels). However, in this situation, Regulus will usually get all of the actual kills while I simply get ridiculous amounts of assists. In fact, Regulus snipe builds will almost always be getting kills based on their teammates' performances, as Regulus is more often than not applying the finishing blow. Therefore, this fact leads me to point out two major things that newer players NEED to keep in mind...
1.) Know how to spend money.
The major problem I had in this game was the fact that I was getting very limited cash (relative to Regulus) because I kept getting assists. We had war rank 10 when they had war rank 6 because our constant killing of them served to grant us basically all map control. Yet NO castle upgrades were being bought, and I had to continue to beef up my gear in order to do my whole "run and chop while getting beat on" routine that was allowing Regulus to get his snipe kills (and I still bought things like experience, income upgrade, etc). I honestly don't know what he was doing with all his money, because I didn't notice his gear getting that much better. Long story short, they got giants and we did not and we lost that match.
To recap:Don't hoard gold and don't skimp out on citidel upgrades if you're yanking in all these kills, because you have most of your team's money!
2.) Stop getting killed.
New Regulus players seem to have this syndrome in that they have convinced themselves of being bad-asses on the field because they can take someone out from across the map. This leads them to wanting to face people head on, thinking they can just piss excellence all over that UB or that Rook. Many a time in the game mentioned above, I'd leave my partner temporarily to grab a flag in a different lane while he would farm creeps. Then the two enemy DG's would come in and he'd pop orb of defiance and wait for me to get back. Now, I had speed enhancing items, but cmon. Between the enemy Oak's Pentinence and the TB's frost spells, the scene would turn into Regulus running for his life back to base and I doing my best to whallop his attackers, who by and large ignored me. Then he would die. Sometimes, I would manage to kill one of his pursuers near our towers, but sometimes that didnt happen, and depending on how long it took me to get to them and how much damage I inflicted before Regulus died, sometimes they would just turn around and kill ME, as well.
The advice I give here to Regulus players is, if you're out there unsupported on the map, and a creep wave of yours reveals an enemy DG who you KNOW you can't outrun effectively heading in your direction, don't wait until he's fucking on top of you to run. Recognize that he is likely coming to eviscerate your nuts, and switch lanes/get help/flee. Recognize that you can get all the kills in the world and still lose the game if you manage to die so often that the opponent still has a steady income. Snipe build Regulus (and, to a lesser extent, assassin build Oak) suffer from late game efficiency because you're relying on abilities, which don't scale well after a certain point. So if you're planning on getting those kills early on, don't give the enemy the cash to hang in the game.