At the beginning of combat on your turn, up to one target land you control becomes an X/X green and blue Bird creature with flying and haste until end of turn, where X is the number of cards in your hand. It's still a land.
Whenever a land creature you control deals combat damage to a player, draw a card.
Jolrael turns a land into a big flying beater each combat (sized by your hand count) and refunds cards whenever land creatures connect, so you fuel a card-advantage engine while attacking. The deck wants to stay land-rich, keep its hand full, and animate lands to swing and draw. You grind out the table, then close with one big evasive turn.
Built-in repeatable card draw that snowballs as you stay full of cards
Cheap, recurable threat — animated lands dodge most board wipes and the body comes back via your land base
Synergizes with classic GU value engines and ramp to power up the X/X size
Flying haste threat every turn pressures life totals and planeswalkers
Animated lands are vulnerable to spot removal and Wasteland-style land destruction, costing you mana and a creature
Heavily reliant on a high hand count; if you empty your hand the Birds get tiny
No built-in protection — Jolrael dies to any removal and the engine stalls
Two-color GU lacks easy mass removal and struggles against fast combo