End-game strategies, huh? Well I have way too much time in game so I got ya covered. Here ya go!
-1: If you feel you cannot attack your desired target, don't. Wait until you feel comfortable with a good set of items and go ham. There's no shame in losing, after all it's online and no pro pvp matches exist, for eggwars at least.
-2: Keep a good lookout. It's not easy to do, but easier with friends. When I'm in a base alone, I usually come outside or get a high point so I can see all around my island around every 30 seconds to check for bridges or "pearlable" players.
-3: Middle control is essential! Middle's abundance of generators allows you to get prepared very quickly. Keeping one of your players at middle or by spending a lot of time at middle on solo, you'll have an advantage.
-4: Buy gear as soon as you can. Unless gens are fairly close (a good example of this is the 4 player map Kingdom, and a bad example of this is the 3 player map Fairground) at middle, do not stay extra time to get more cash. You'll end up being hunted.
-5: DITCH! This is by far one of my favorite strategies as it can be enraging for your opponent and extremely beneficial to you if used correctly! If your island defenses are being quickly cut through and you know there is no quick way to stop someone from breaking your egg, frickin' RUN! Also, like I said, do it when you know your egg will get broken, not when it is. Run to an island across the map, not their island, and pick up some supplies from mid on your way, and do not go back to your island. Once you reach a good island, go in, buy gear and upgrade gens, and destroy the bridge to it if you are not under bowfire. This way, they will have a harder time finding you, and you'll have a chance to get yourself back up. Lastly, building on this one, sometimes saving a team member is not entirely worth it. After all, it's an online game and what you do so long as it's not mean doesn't matter in the long run.
-6: Almost infinite health. Now this one is a very cool strategy but only effective if used exactly right. So, this one has a lot of requirements as well, but using it correctly keeps you alive for a very long time! First off, I recommend only using this strategy as your so called "post game", so make sure you have iron armor. Secondly, get LOTS of non-enchanted golden apples, I'd say 20+ per opposing player you're going to attack. Now, here's where you use it. Every time your health bar is missing 3 OR MORE WHOLE HEARTS, eat a golden apple. I've very, very rarely been killed using this. Sadly, it's not too effective against hackers as they just keep hitting and you'll spend your time eating.
-7: Here's my last one, yet very helpful. Always know where your player is in relation to the environment. Now I'm not saying play Eggwars in "F5 mode" so you're looking at your player, but know the blocks around you and always know 2 main things:
-Know where the closest edge is, where you can get knocked off
-Know where the closest wall is
Stay well away from edges and don't try to hit your opponent off unless they're very close to the edge. Also know where walls are and make your own, being bow spammed off is a fate no player deserves.
Have fun with these and good luck!