Giants are fast becoming the master race. In the next update they will acquire what is pretty much an upgraded version of human FH, get 2 more skills that make their melee abilities even stronger, and new weapons with status effects that buffs those skills. It's only a matter of time before they get more ranged abilities that are really similar to bows, but are far superior with weapons that boost them EVEN MORE. Then they will get 350 physical and magic protection!
Soloing phantasm is really not as hard as people make it out to be. Especially now, since we got a huge buff for hp and mp. The new renown gives you a whopping 500+ more hp and mp. I saw lots of peeps with phantasm breaker on Alexina nowadays. Soloing phantasm efficiently however is a different matter, and very few people are capable of doing it, but based on what you said, I assumed you just want to be able to solo it once.
That said, I'm a human so my advice don't really work for elves but elves should be able to solo phantasm much more easier than humans and giants. My biggest problem during my solo run is during the boss fight but elves can just cheese it with deer hide. Heck, you can use the deer hide method in all rooms I think. Hide is so broken. You said you don't have crystal deer, so you should make some money and buy them off other players. If you're making this as your goal, you should be able to at least earn that much money. A phoenix pet is useful as well since it's the only thing that can resurrect you upon death in phantasm, and the pet itself is not that expensive.
While you're working on your dex, you should hoard tons of recovery potions and mp pots and weapon power pot (or just use bone chips). After you finished your preparations, you can practice in mirror first. You don't really need to run it in a party to get used to the mechanism (party runs may be different from solo too), you should be able to familiarize yourself with the mechanics by watching some phantasm videos and in a few practice runs. I did my solo without ever running phantasm in a party.
It's also a good idea to work on your divine link subskills, especially guardian oath and sacred revival. Sacred revival is most essential as it can revive your pet up to 3 times at max level but level 8 should be enough (2 times revival).