When it comes to downloading torrents and magnets, I normally stick to qBittorrent on my laptop. It is easy to use, fast, smooth and light. But when you are connected to a remote machine through a terminal the situation changes abruptly. You don’t have any X support (but maybe your server is connected to the internet over a 1GBPS line waiting to be utilized). You get your hands dirty with rTorrent. Written in C++, exceptionally light, incredibly fast and running on a thin library, rTorrent is bound to amaze you once you get hold of the basic usage. It has all the essential functionality of a powerful torrent (and magnet) client. Here are some articles explaining navigation, configuration etc. at a very granular level:

To install rTorrent on Ubuntu:

$ sudo apt-get install rtorrent

Some useful tips for navigation: while searching for a file, Tab completes the directories. And you can open a torrent file directly using

$ rtorrent mytorrent.torrent OR URL
//note: URL works for torrent only

Now you are going to ask how to close the terminal and keep rTorrent running in the background. Run:

$ dtach -A /tmp/rtorsocket -z rtorrent

To resume, run:

$ dtach -a /tmp/mytorrent.torrent

Remember not to close the terminal with Ctrl-D. Either close it by clicking the close button or use Ctrl+\. More methods to detach console processes and keep them running in the background here.

rTorrent can also download torrents if you provide the direct URL to rTorrent as a parameter while starting it.

Webpage: rTorrent